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美国科罗拉多州大学关于在噪声环境下对大量连续语音识别系统的改进---------噪声环境下说话声音的识别工作简介在本文中，我们报道美国科罗拉多州大学关于噪声环境下海军研究语音词汇系统方面的最新改进成果。

特别地,我们介绍在有限语音数据的前提下，为了了解不确定观察者和变化的环境的任务(或调查方法)，我们必须在提高听觉和语言模式方面努力下工夫。

在大量连续词汇语音识别系统中,我们将展开MAPLR自适应方法研究。

它包括单个或多重最大可能线形回归。

当前噪声环境下语音识别系统使用了大量声音词汇识别的声音识别引擎。

这种引擎在美国科罗拉多州大学目前得到了飞速的发展，本系统在噪声环境下说话声音系统(SPINE-2)评价数据中单词错识率表现为30.5%，比起2001年的SPINE-2来,在相关词汇错识率减少16%。

1.介绍为获得噪声环境下的有活力的连续声音系统的声音，我们试图在艺术的领域做出计算和提出改善，这个工作有几方面的难点：依赖训练的有限数据工作；在训练和测试中各种各样的军事噪声存在；在每次识别适用性阶段中，不可想象的听觉溪流和有限数量的声音。

在2000年11月的SPIN-1和2001年11月SPIN-2中，海军研究词汇通过DARPT在工作上给了很大的帮助。

在2001年参加评估的种类有：SPIIBM,华盛顿大学，美国科罗拉多州大学，AT&T,奥瑞哥研究所，和梅隆卡内基大学。

它们中的许多先前已经报道了SPINE-1和SPLNE-2工作的结果。

在这方面的工作中不乏表现最好的系统.我们在特性和主模式中使用了自适应系统，同时也使用了被用于训练各种参数类型的多重声音平行理论(例如MFCC、PCP等)。

其中每种识别系统的输出通常通过一个假定的熔合的方法来结合。

这种方法能提供一个单独的结果，这个结果的错误率将比任何一个单独的识别系统的结果要低。

美国科罗拉多州大学参加了SPIN-2和SPIN-1的两次评估工作。

我们2001年11月的SPIN-2是美国科罗拉多州大学识别系统基础上第一次被命名为SONIC(大量连续语音识别系统)的。

通信类英文文献

the Evolution of Modern MobileCommunication TechnologyRadha PoovendranIn now highly the informationization society, the information and the correspondence have become the modern society “the life”. The information exchange mainly relies on the computer correspondence, but corresponds takes the transmission method, with the sensing technology, the computer technology fuses mutually, has become in the 21st century the international society and the world economic development powerful engine. In order to of adapt the time request, the new generation of mobile communication technology seasonable and lives, the new generation of mobile communication technology is the people said that third generation's core characteristic is the wide band addressing turns on non-gap roaming between the rigid network and numerous different communications system's, gains the multimedia communication services.Along with the time progress, the technical innovation, people's life request's enhancement, the mobile communication technology renewal speed is quite astonishing, almost every other ten year mobile communication technology has a transformation update, from the 1980s “the mobile phone” to present's 3G handset, during has had two mobile communication technology transformation, transits from 1G AMPS to 2GGSM, from GSM to IMT-2000 (i.e. 3G technology). Knows modern on me the mobile communication technology to have the following several aspect important technology:1. wideband modulation and multiple access techniqueThe wireless high speed data transmission cannot only depend on the frequency spectrum constantly the expansion, should be higher than the present number magnitude at least in the frequency spectrum efficiency, may use three technologies in the physical level, namely OFDM, UWB and free time modulation code. OFDM with other encoding method's union, nimbly OFDM and TDMA, FDMA, CDMA, SDMA combines the multiple access technique.In the 1960s the OFDM multi-channel data transmission has succeeded uses in Kineplex and the Kathryn high frequency military channels. OFDM has used in 1.6 Mbit/s high bit rate digital subscriber line (HDSL), 6 Mbit/s asymmetrical digital subscriber line (ADSL), 100 Mbit/s really high speed figure subscriber's line (VDSL), digital audio frequency broadcast and digital video broadcast and so on. OFDM applies on 5 GHz provides 54 Mbit/s wireless local network IEEE 802.11 a and IEEE 802.11g, high performance this region network Hiper LAN/2 and ETSI-BRAN, but also takes metropolitan area network IEEE 802.16 and the integrated service digit broadcast (ISDB-T) the standard. Compares with the single load frequency modulation system servicepattern, the OFDM modulation service pattern needs to solve the relatively big peak even power ratio (PAPR, Peak to Average Power Ratio) and to the frequency shifting and the phase noise sensitive question.High speed mobile communication's another request is under the wide noise bandwidth, must demodulate the signal-to-noise ratio to reduce as far as possible, thus increases the cover area. May adopt the anti-fading the full start power control and the pilot frequency auxiliary fast track demodulation technology, like the frequency range anti-fading's Rake receive and the track technology, the OFDMA technology which declines from the time domain and the frequency range resistance time and the frequency selectivity, the link auto-adapted technology, the union coding technique.2. frequency spectrum use factor lift techniqueThe fundamental research pointed out: In the independent Rayleigh scattering channel, the data rate and the antenna several tenth linear relationships, the capacity may reach Shannon 90%. Is launching and the receiving end may obtain the capacity and the frequency spectrum efficiency gain by the multi-antenna development channel space. The MIMO technology mainly includes the spatial multiplying and the space diversity technology, concurrent or the salvo same information enhances the transmission reliability on the independent channel.Receives and dispatches the bilateral space diversity is thehigh-capacity wireless communication system uses one of technical. Bell Lab free time's opposite angle BLAST (D-BLAST) capacity increase to receive and dispatch the bilateral smallest antenna number in administrative levels the function. The cross time domain which and the air zone expansion signal constitutes using MIMO may also resist the multi-diameter disturbance. V-BLAST system when indoor 24~34 dB, the frequency spectrum use factor is 20~40 bit/s/Hz. But launches and the receiving end uses 16 antennas, when 30 dB, the frequency spectrum use factor increases to 60~70 bit/s/Hz.The smart antenna automatic tracking needs the signal and the auto-adapted free time processing algorithm, produces the dimensional orientation wave beam using the antenna array, causes the main wave beam alignment subscriber signal direction of arrival through the digital signal processing technology, the side lobe or zero falls the alignment unwanted signal direction of arrival. The auto-adapted array antennas (AAA, Adaptive Array Antennas) disturbs the counter-balance balancer (ICE, Interference Canceling Equalizer) to be possible to reduce disturbs and cuts the emissive power.3. software radio technologyThe software radio technology is in the hardware platform through the software edition by a terminal implementation different system in many kinds of communication services. It uses the digital signalprocessing language description telecommunication part, downloads the digital signal processing hardware by the software routine (DSPH, Digital Signal Pocessing Hardware). By has the general opening wireless structure (OW A, Open Wireless Architecture), compatible many kinds of patterns between many kinds of technical standards seamless cut.UWB is also called the pulse to be radio, the modulation uses the pulse width in the nanosecond level fast rise and the drop pulse, the pulse cover frequency spectrum from the cocurrent to the lucky hertz, does not need in the radio frequency which the convention narrow band frequency modulation needs to transform, after pulse formation, may deliver directly to the antenna launch.4. software radio technologyThe software radio technology is in the hardware platform through the software edition by a terminal implementation different system in many kinds of communication services. It uses the digital signal processing language description telecommunication part, downloads the digital signal processing hardware by the software routine (DSPH, Digital Signal Pocessing Hardware). By has the general opening wireless structure (OW A, Open Wireless Architecture), compatible many kinds of patterns between many kinds of technical standards seamless cut.5. network security and QoSQoS divides into wireless and the wired side two parts, wirelessside's QoS involves the radio resource management and the dispatch, the admission control and the mobility management and so on, the mobility management mainly includes the terminal mobility, individual mobility and service mobility. Wired side's QoS involves based on the IP diffSer discrimination service and the RSVP end-to-end resources reservation mechanism. Mechanism maps the wireless side IP diffSer IP the QoS. Network security including network turning on security, core network security, application security, safety mechanism visibility and configurable.In the above modern mobile communication key technologies's foundation, has had the land honeycomb mobile communication, the satellite communication as well as the wireless Internet communication, these mailing address caused the correspondence appearance to have the huge change, used the digital technique the modern wireless communication already to permeate the national economy each domain and people's daily life, for this reason, we needed to care that its trend of development, hoped it developed toward more and more convenient people's life's direction, will let now us have a look at the modern mobile communication the future trend of development.modern mobile communication technological development seven new tendencies :First, mobility management already from terminal management toindividual management and intelligent management development Second, network already from synchronized digital circuit to asynchronous digital grouping and asynchronous transfer mode (ATM) development;the three, software's developments actuated from the algorithm to the procedure-oriented and face the goal tendency development;the four, information processing have developed from the voice to the data and the image;five, wireless frequency spectrum processing already from narrow band simulation to the narrow band CDMA development;the six, computers have developed from central processing to the distributional server and intellectualized processing;the seven, semiconductor devices have developed from each chip 16,000,000,000,000 /150MHz speed VLSI to 0.5 /350MHz speed VLSI and 2,000,000,000,000,000 /550MHz speed VLSI.Under this tendency's guidance, the mobile service rapid development, it satisfied the people in any time, any place to carry on the correspondence with any individual the desire. The mobile communication realizes in the future the ideal person-to-person communication service way that must be taken. In the information support technology, the market competition and under the demand combined action, the mobile communication technology's development isprogresses by leaps and bounds, presents the following several general trends: 1) network service digitization, grouping; 2) networking wide band; 3) networking intellectualization; 4) higher frequency band; 5) more effective use frequency; 6) each kind of network tends the fusion. The understanding, grasps these tendencies has the vital practical significance to the mobile communication operator and the equipment manufacturer.。

数据通信毕业论文外文文献英文翻译

郑州轻工业学院本科毕业设计（论文）——英文翻译题目差错控制编码解决加性噪声的仿真学生姓名专业班级通信工程05-2 学号 12院（系）计算机与通信工程学院指导教师完成时间 2009年4月26日英文原文:Data communicationsGildas Avoine and Philippe OechslinEPFL, Lausanne, Switzerlandfgildas.avoine, philippe.oechsling@ep.chAbstractData communications are communications and computer technology resulting from the combination of a new means of communication. To transfer information between the two places must have transmission channel, according to the different transmission media, there is wired data communications and wireless data communications division. But they are through the transmission channel data link terminals and computers, different locations of implementation of the data terminal software and hardware and the sharing of information resources.1 The development of data communicationsThe first phase: the main language, through the human, horsepower, war and other means of transmission of original information.Phase II: Letter Post. (An increase means the dissemination of information)The third stage: printing. (Expand the scope of information dissemination)Phase IV: telegraph, telephone, radio. (Electric to enter the time)Fifth stage: the information age, with the exception of language information, there are data, images, text and so on.1.1 The history of modern data communicationsCommunication as a Telecommunications are from the 19th century, the beginning Year 30. Faraday discovered electromagnetic induction in 1831. Morse invented telegraph in 1837. Maxwell's electromagnetic theory in 1833. Bell invented the telephone in 1876. Marconi invented radio in 1895. Telecom has opened up in the new era. Tube invented in 1906 in order to simulate the development of communications.Sampling theorem of Nyquist criteria In 1928. Shannong theorem in 1948. The invention of the 20th century, thesemiconductor 50, thereby the development of digital communications. During the 20th century, the invention of integrated circuits 60. Made during the 20th century, 40 the concept of geostationary satellites, but can not be achieved. During the 20th century, space technology 50. Implementation in 1963 first synchronized satellite communications. The invention of the 20th century, 60 laser, intended to be used for communications, was not successful. 70 The invention of the 20th century, optical fiber, optical fiber communications can be developed.1.2 Key figuresBell (1847-1922), English, job in London in 1868. In 1871 to work in Boston. In 1873, he was appointed professor at Boston University. In 1875, invented many Telegram Rd. In 1876, invented the telephone. Lot of patents have been life. Yes, a deaf wife.Marconi (1874-1937), Italian people, in 1894, the pilot at his father's estate. 1896, to London. In 1897, the company set up the radio reported. In 1899, the first time the British and French wireless communications. 1916, implementation of short-wave radio communications. 1929, set up a global wireless communications network. Kim won the Nobel Prize. Took part in the Fascist Party.1.3 Classification of Communication SystemsAccording to type of information: Telephone communication system, Cable television system ,Data communication systems.Modulation by sub: Baseband transmission,Modulation transfer.Characteristics of transmission signals in accordance with sub: Analog Communication System ,Digital communication system.Transmission means of communication system: Cable Communications,Twisted pair, coaxial cable and so on.And long-distance telephone communication. Modulation: SSB / FDM. Based on the PCM time division multiple coaxial digital base-band transmission technology. Will gradually replace the coaxial fiber.Microwave relay communications:Comparison of coaxial and easy to set up, low investment, short-cycle. Analog phone microwave communications mainly SSB / FM /FDM modulation, communication capacity of 6,000 road / Channel. Digital microwave using BPSK, QPSK and QAM modulation techniques. The use of 64QAM, 256QAM such as multi-level modulation technique enhance the capacity of microwave communications can be transmitted at 40M Channel 1920 ~ 7680 Telephone Rd PCM figure.Optical Fiber Communication: Optical fiber communication is the use of lasers in optical fiber transmission characteristics of long-distance with a large communication capacity, communication, long distance and strong anti-interference characteristics. Currently used for local, long distance, trunk transmission, and progressive development of fiber-optic communications network users. At present, based on the long-wave lasers and single-mode optical fiber, each fiber road approach more than 10,000 calls, optical fiber communication itself is very strong force. Over the past decades, optical fiber communication technology develops very quickly, and there is a variety of applications, access devices, photoelectric conversion equipment, transmission equipment, switching equipment, network equipment and so on. Fiber-optic communications equipment has photoelectric conversion module and digital signal processing unit is composed of two parts.Satellite communications: Distance communications, transmission capacity, coverage, and not subject to geographical constraints and high reliability. At present, the use of sophisticated techniques Analog modulation, frequency division multiplexing and frequency division multiple access. Digital satellite communication using digital modulation, time division multiple road in time division multiple access.Mobile Communications: GSM, CDMA. Number of key technologies for mobile communications: modulation techniques, error correction coding and digital voice encoding. Data Communication Systems.1.4 Five basic types of data communication system:（1）Off-line data transmission is simply the use of a telephone or similar link to transmit data without involving a computer system.The equipment used at both ends of such a link is not part of a computer, or at least does not immediately make the data available for computer process, that is, the data when sent and / or received are 'off-line'.This type of data communication is relatively cheap and simple.（2）Remote batch is the term used for the way in which data communication technology is used geographically to separate the input and / or output of data from the computer on which they are processed in batch mode.（3）On-line data collection is the method of using communications technology to provide input data to a computer as such input arises-the data are then stored in the computer (say on a magnetic disk) and processed either at predetermined intervals or as required.（4）Enquiry-response systems provide, as the term suggests, the facility for a user to extract information from a computer.The enquiry facility is passive, that is, does not modify the information stored.The interrogation may be simple, for example, 'RETRIEVE THE RECORD FOR EMPLOYEE NUMBER 1234 'or complex.Such systems may use terminals producing hard copy and / or visual displays.（5）Real-time systems are those in which information is made available to and processed by a computer system in a dynamic manner so that either the computer may cause action to be taken to influence events as they occur (for example as in a process control application) or human operators may be influenced by the accurate and up-to-date information stored in the computer, for example as in reservation systems.2 Signal spectrum with bandwidthElectromagnetic data signals are encoded, the signal to be included in the data transmission. Signal in time for the general argument to show the message (or data) as a parameter (amplitude, frequency or phase) as the dependent variable. Signal of their value since the time variables are or not continuous, can be divided into continuous signals and discrete signals; according to whether the values of the dependent variable continuous, can be divided into analog signals and digital Signal.Signals with time-domain and frequency domain performance of the two most basic forms and features. Time-domain signal over time to reflect changing circumstances. Frequency domain characteristics of signals not only contain the same information domain, and the spectrum of signal analysis, can also be a clear understanding of the distribution ofthe signal spectrum and share the bandwidth. In order to receive the signal transmission and receiving equipment on the request channel, Only know the time-domain characteristics of the signal is not enough, it is also necessary to know the distribution of the signal spectrum. Time-domain characteristics of signals to show the letter .It’s changes over time. Because most of the signal energy is concentrated in a relatively narrow band, so most of our energy focused on the signal that Paragraph referred to as the effective band Bandwidth, or bandwidth. Have any signal bandwidth. In general, the greater the bandwidth of the signal using this signal to send data Rate on the higher bandwidth requirements of transmission medium greater. We will introduce the following simple common signal and bandwidth of the spectrum.More or less the voice signal spectrum at 20 Hz ~ 2000 kHz range (below 20 Hz infrasound signals for higher than 2000 KHz. For the ultrasonic signal), but with a much narrower bandwidth of the voice can produce an acceptable return, and the standard voice-frequency signal gnal 0 ~ 4 MHz, so the bandwidth of 4 MHz.As a special example of the monostable pulse infinite bandwidth. As for the binary signal, the bandwidth depends on the generalThe exact shape of the signal waveform, as well as the order of 0,1. The greater the bandwidth of the signal, it more faithfully express the number of sequences.3 The cut-off frequency channel with bandwidthAccording to Fourier series we know that if a signal for all frequency components can be completely the same through the transmission channel to the receiving end, then at the receiving frequency components of these formed by stacking up the signal and send the signal side are exactly the same, That is fully recovered from the receiving end of the send-side signals. But on the real world, there is no channel to no wear and tear through all the Frequency components. If all the Fourier components are equivalent attenuation, then the signal reception while Receive termination at an amplitude up Attenuation, but the distortion did not happen. However, all the transmission channel and equipment for different frequency components of the degree of attenuation is differentSome frequency components almost no attenuation, and attenuation of some frequency components by anumber, that is to say, channel also has a certain amount of vibrationIncrease the frequency characteristics, resulting in output signal distortion. Usually are frequency of 0 Hz to fc-wide channel at Chuan harmonic lost during the attenuation does not occur (or are a very small attenuation constant), whereas in the fc frequency harmonics at all above the transmission cross Decay process a lot, we put the signal in the transmission channel of the amplitude attenuation of a component to the original 0.707(that is, the output signal Reduce by half the power) when the frequency of the corresponding channel known as the cut-off frequency (cut - off frequency).Cut-off frequency transmission medium reflects the inherent physical properties. Other cases, it is because people interested in Line filter is installed to limit the bandwidth used by each user. In some cases, because of the add channel Two-pass filter, which corresponds to two-channel cut-off frequency f1 and f2, they were called up under the cut-off frequency and the cut-off frequency.This difference between the two cut-off frequency f2-f1 is called the channel bandwidth. If the input signal bandwidth is less than the bandwidth of channel, then the entire input signal Frequency components can be adopted by the Department of channels, which the letter Road to be the output of the output waveform will be true yet. However, if the input signal bandwidth greater than the channel bandwidth, the signal of a Frequency components can not be more on the channel, so that the signal output will be sent with the sending end of the signal is somewhat different, that is produced Distortion. In order to ensure the accuracy of data transmission, we must limit the signal bandwidth.4 Data transfer rateChannel maximum data transfer rate Unit time to be able to transfer binary data transfer rate as the median. Improve data transfer rate means that the space occupied by each Reduce the time that the sequence of binary digital pulse will reduce the cycle time, of course, will also reduce the pulse width.The previous section we already know, even if the binary digital pulse signal through a limited bandwidth channel will also be the ideal generated wave Shape distortion, and when must the input signal bandwidth, the smaller channel bandwidth, output waveformdistortion will be greater. Another angle Degree that when a certain channel bandwidth, the greater the bandwidth of the input signal, the output signal the greater the distortion, so when the data transmissionRate to a certain degree (signal bandwidth increases to a certain extent), in the on-channel output signal from the receiver could not have been Distortion of the output signal sent to recover a number of sequences. That is to say, even for an ideal channel, the limited bandwidth limit System of channel data transfer rate.At early 1924, H. Nyquist (Nyquist) to recognize the basic limitations of this existence, and deduced that the noise-free Limited bandwidth channel maximum data transfer rate formula. In 1948, C. Shannon (Shannon) put into the work of Nyquist 1 Step-by-step expansion of the channel by the random noise interference. Here we do not add on to prove to those now seen as the result of a classic.Nyquist proved that any continuous signal f (t) through a noise-free bandwidth for channel B, its output signal as a Time bandwidth of B continuous signal g (t). If you want to output digital signal, it must be the rate of g (t) for interval Sample. 2B samples per second times faster than are meaningless, because the signal bandwidth B is higher than the high-frequency component other than a letter has been Road decay away. If g (t) by V of discrete levels, namely, the likely outcome of each sample for the V level of a discrete one, The biggest channel data rate Rm ax as follows:Rmax = 2Blog 2 V (bit / s)For example, a 3000 Hz noise bandwidth of the channel should not transmit rate of more than 6,000 bits / second binary digital signal.In front of us considered only the ideal noise-free channel. There is noise in the channel, the situation will rapidly deteriorate. Channel Thermal noise with signal power and noise power ratio to measure the signal power and noise power as the signal-to-noise ratio (S ignal - to -- Noise Ratio). If we express the signal power S, and N express the noise power, while signal to noise ratio should be expressed as S / N. However, people Usually do not use the absolute value of signal to noise ratio, but the use of 10 lo g1 0S / N to indicate the units are decibels (d B). For the S / N equal 10 Channel, said its signal to noise ratio for the 1 0 d B; the same token, if the channel S / N equal to one hundred, then the signal to noiseratio for the 2 0 d B; And so on. S hannon noise channel has about the maximum data rate of the conclusions are: The bandwidth for the BH z, signal to noise ratio for the S / N Channel, the maximum data rate Rm ax as follows:Rmax = Blog 2 (1 + S / N) (bits / second)For example, for a bandwidth of 3 kHz, signal to noise ratio of 30 dB for the channel, regardless of their use to quantify the number of levels, nor Fast sampling rate control, the data transfer rate can not be greater than 30,000 bits / second. S h a n n o n the conclusions are derived based on information theory Out for a very wide scope, in order to go beyond this conclusion, like you want to invent perpetual motion machine, as it is almost impossible.It is worth noting that, S hannon conclusions give only a theoretical limit, and in fact, we should be pretty near the limit Difficult.SUMMARYMessage signals are (or data) of a magnetic encoder, the signal contains the message to be transmitted. Signal according to the dependent variable Whether or not a row of values, can be classified into analog signals and digital signals, the corresponding communication can be divided into analog communication and digital communication.Fourier has proven: any signal (either analog or digital signal) are different types of harmonic frequencies Composed of any signal has a corresponding bandwidth. And any transmission channel signal attenuation signals will, therefore, Channel transmission of any signal at all, there is a data transfer rate limitations, and this is Chengkui N yquist (Nyquist) theorem and S hannon (Shannon) theorem tells us to conclusions.Transmission medium of computer networks and communication are the most basic part of it at the cost of the entire computer network in a very Large proportion. In order to improve the utilization of transmission medium, we can use multiplexing. Frequency division multiplexing technology has many Road multiplexing, wave division multiplexing and TDM three that they use on different occasions.Data exchange technologies such as circuit switching, packet switching and packetswitching three have their respective advantages and disadvantages. M odem are at Analog phone line for the computer's binary data transmission equipment. Modem AM modulation methods have, FM, phase modulation and quadrature amplitude modulation, and M odem also supports data compression and error control. The concept of data communications Data communication is based on "data" for business communications systems, data are pre-agreed with a good meaning of numbers, letters or symbols and their combinations.参考文献[1]C.Y.Huang and A.Polydoros,“Two small SNR classification rules for CPM,”inProc.IEEE Milcom,vol.3,San Diego,CA,USA,Oct.1992,pp.1236–1240.[2]“Envelope-based classification schemes for continuous-phase binary Frequency-shift-keyed modulations,”in Pr oc.IEEE Milcom,vol.3,Fort Monmouth,NJ,USA,Oct.1994,pp. 796–800.[3]A.E.El-Mahdy and N.M.Namazi,“Classification of multiple M-ary frequency-shift keying over a rayleigh fading channel,”IEEE m.,vol.50,no.6,pp.967–974,June 2002.[4]Consulative Committee for Space Data Systems(CCSDS),Radio Frequency and Modulation SDS,2001,no.401.[5]E.E.Azzouz and A.K.Nandi,“Procedure for automatic recognition of analogue and digital modulations,”IEE mun,vol.143,no.5,pp.259–266,Oct.1996.[6]A.Puengn im,T.Robert,N.Thomas,and J.Vidal,“Hidden Markov models for digital modulation classification in unknown ISI channels,”in Eusipco2007,Poznan,Poland, September 2007,pp.1882–1885.[7]E.Vassalo and M.Visintin,“Carrier phase synchronization for GMSK signals,”I nt.J.Satell. Commun.,vol.20,no.6,pp.391–415,Nov.2002.[8]J.G.Proakis,Digital Communications.Mc Graw Hill,2001.[9]L.Rabiner,“A tutorial on hidden Markov models and selected applications in speechrecognition,”Proc.IEEE,vol.77,no.2,pp.257–286,1989.英文译文：数据通信Gildas Avoine and Philippe OechslinEPFL, Lausanne, Switzerlandfgildas.avoine, philippe.oechsling@ep.ch摘要数据通信是通信技术和计算机技术相结合而产生的一种新的通信方式。

通信工程外文资料翻译2篇

南京理工大学毕业设计(论文)外文资料翻译学院（系）：电子工程与光电技术学院专业：通信工程姓名：学号：外文出处：1. IEEE TRANSACTIONS ONANTENNAS AND PROPAGATION,VOL. 53,NO.9, SEPTEMBER 20052. IEEE TRANSACTIONS ONMICROWA VE THEORY ANDTECHNIQUES, VOL. 53,NO.6,JUNE 2005附件：1.外文资料翻译译文一；2.外文资料翻译译文二；3.外文原文一；4.外文原文二；注：请将该封面与附件装订成册。

附件1：外文资料翻译译文一在单封装超宽波段无线通信中使用LTCC技术的平面天线作者：Chen Ying and Y.P.Zhang摘要：此通讯提出了一个使用低温度共烧陶瓷技术的平面天线用于超宽频带（UWB）无线通信的单封装解决方案。

该天线具有一个通过微带线反馈的椭圆形的辐射体。

该辐射体和微带线拥有与其它UWBR电路相同的接地板。

实验结果表明原型天线已达到110.9％的带宽，从1.34到5.43 dBi的增益，宽模式和频率从3到10.6GHz 的相对恒定的群延迟。

更多地还发现，标准化天线辐射功率谱密度基本符合FCCS 对于室内UWB系统的发射限制。

关键词：低温共烧陶瓷（LTCC），平面天线，超宽频带（UWB）。

一、引言现在，发展用于窄范围高速度的无线通信网络的超宽频带（UWB）无线电是一个研究热点。

超宽带无线电利用一个7.5 GHz的超宽带宽来交换信息。

使用这样大的带宽，在使U超宽带无线电发挥它最大的作用上存在一些问题.其中的一个主要问题是用于移植系统的超宽带天线的设计。

好的超宽带天线应具有较低的回波损耗，全向辐射模式，从3.1至10.6 GHz的超宽带宽下的高效率，同时也应当满足FCCS规定的发射限制。

现在已经有一些超宽带天线，如钻石偶极子和互补缝隙天线。

它们已被证明适用于超宽带无线电[1] - [4]。

[最新]通信专业的外文及外文翻译

Research,,,,,on,,,,,Carrier,,,,,T racking,,,,,in,,,,,Hybrid,,, ,,DS/FH,,,,,Spread,,,,,Spectrum,,,,,TT&C,,,,,SystemAbstractBecause,,,,,of,,,,,the,,,,,effect,,,,,of,,,,,carrier,,,,,frequency,,,,,hopping,,,,,,the,,,,,inp ut,,,,,IF,,,,,signal,,,,,of,,,,,carrier,,,,,tracking,,,,,loop,,,,,in,,,,,DS/FHSS,,,,,(Direct,,,,,Sequ ence/Frequency,,,,,Hopping,,,,,Spread,,,,,Spectrum),,,,,TT&C,,,,,(Telemetry,,,,,,Trackin g,,,,,&,,,,,Command),,,,,System,,,,,is,,,,,characterized,,,,,by,,,,,the,,,,,Doppler,,,,,frequen cy,,,,,agile.,,,,,The,,,,,tracking,,,,,loop,,,,,will,,,,,shift,,,,,to,,,,,the,,,,,frequency,,,,,step,,,,, response,,,,,state,,,,,ceaselessly,,,,,and,,,,,the,,,,,measurement,,,,,resolution,,,,,severely,,, ,,decline,,,,,,even,,,,,the,,,,,loop,,,,,is,,,,,likely,,,,,to,,,,,be,,,,,unlocked.,,,,,This,,,,,paper,,,, ,presents,,,,,a,,,,,carrier,,,,,tracking,,,,,loop,,,,,aided,,,,,by,,,,,frequency,,,,,hopping,,,,,pat tern.,,,,,In,,,,,order,,,,,to,,,,,keep,,,,,the,,,,,stability,,,,,of,,,,,the,,,,,tracking,,,,,loop,,,,,,the,, ,,,Doppler,,,,,frequency,,,,,agility,,,,,in,,,,,the,,,,,next,,,,,frequency,,,,,hopping,,,,,dwell,,,, ,is,,,,,estimated,,,,,and,,,,,timely,,,,,compensated,,,,,to,,,,,the,,,,,frequency,,,,,adjustment, ,,,,of,,,,,carrier,,,,,NCO,,,,,according,,,,,to,,,,,the,,,,,preset,,,,,frequency,,,,,hopping,,,,,pat tern,,,,,and,,,,,current,,,,,spacecraft,,,,,velocity.,,,,,Simulation,,,,,results,,,,,show,,,,,that,,, ,,this,,,,,method,,,,,effectively,,,,,eliminates,,,,,the,,,,,instability,,,,,due,,,,,to,,,,,carrier,,,,, frequency,,,,,hopping,,,,,,and,,,,,the,,,,,resolution,,,,,of,,,,,loop,,,,,meets,,,,,the,,,,,require ment,,,,,of,,,,,TT&C,,,,,system.,,,,,Keywords：carrier,,,,,tracking；DS/FHSS；frequency,,,,,agility；aided；TT&CI．INTRODUCTIONThe,,,,,main,,,,,function,,,,,of,,,,,TT&C,,,,,(Telemetry,,,,,,Tracking,,,,,and,,,,,Com mand),,,,,system,,,,,is,,,,,ranging,,,,,and,,,,,velocity,,,,,measurement.,,,,,Presently,,,,,,the, ,,,,most,,,,,common,,,,,used,,,,,TT&C,,,,,systems,,,,,are,,,,,unit,,,,,carrier,,,,,system,,,,,an d,,,,,unit,,,,,spread,,,,,spectrum,,,,,system.,,,,,For,,,,,the,,,,,unit,,,,,carrier,,,,,TT&C,,,,,sys tem,,,,,,ranging,,,,,is,,,,,realized,,,,,by,,,,,measuring,,,,,the,,,,,phase,,,,,difference,,,,,betw een,,,,,transmitted,,,,,and,,,,,received,,,,,tones,,,,,,and,,,,,for,,,,,the,,,,,unit,,,,,spread,,,,,sp ectrum,,,,,TT&C,,,,,system,,,,,,according,,,,,to,,,,,the,,,,,autocorrelation,,,,,properties,,,,, of,,,,,PN,,,,,code,,,,,,ranging,,,,,is,,,,,realized,,,,,by,,,,,measuring,,,,,the,,,,,phase,,,,,delay, ,,,,between,,,,,the,,,,,received,,,,,and,,,,,local,,,,,pseudonoise,,,,,(PN),,,,,code.,,,,,V elocity ,,,,,measurement,,,,,in,,,,,both,,,,,of,,,,,TT&C,,,,,systems,,,,,depends,,,,,on,,,,,extracting,, ,,,the,,,,,frequency,,,,,difference,,,,,resulting,,,,,from,,,,,the,,,,,Doppler,,,,,phenomena,,,,, between,,,,,the,,,,,transmitted,,,,,and,,,,,received,,,,,carrier.,,,,,While,,,,,all,,,,,the,,,,,proc esses,,,,,mentioned,,,,,above,,,,,are,,,,,finished,,,,,on,,,,,the,,,,,ground,,,,,of,,,,,high,,,,,res olution,,,,,carrier,,,,,tracking,,,,,,and,,,,,the,,,,,phase,,,,,lock,,,,,loop,,,,,is,,,,,the,,,,,comm on,,,,,used,,,,,method,,,,,to,,,,,implement,,,,,it,,,,,in,,,,,TT&C,,,,,system.,,,,,As,,,,,the,,,,,s pace,,,,,electromagnetism,,,,,environment,,,,,become,,,,,more,,,,,and,,,,,more,,,,,complic ated,,,,,,the,,,,,capability,,,,,of,,,,,anti-jamming,,,,,is,,,,,required,,,,,by,,,,,the,,,,,future,,,,, TT&C,,,,,system,,,,,[1].,,,,,So,,,,,we,,,,,consider,,,,,using,,,,,the,,,,,hybrid,,,,,DS/FHSS,,,, ,(Direct,,,,,Sequence/Frequency,,,,,Hopping,,,,,Spread,,,,,Spectrum),,,,,technology,,,,,to ,,,,,build,,,,,a,,,,,more,,,,,robust,,,,,TT&C,,,,,system.,,,,,,,,,,For,,,,,many,,,,,ordinary,,,,,hybrid,,,,,DS/FHSS,,,,,communication,,,,,systems,,,,,,th e,,,,,most,,,,,important,,,,,function,,,,,is,,,,,demodulating,,,,,data,,,,,but,,,,,not,,,,,measuri ng,,,,,,so,,,,,it,,,,,is,,,,,not,,,,,necessary,,,,,to,,,,,measure,,,,,the,,,,,carrier,,,,,frequency,,,,,p recisely.,,,,,However,,,,,,in,,,,,hybrid,,,,,DS/FHSS,,,,,TT&C,,,,,system,,,,,,measuring,,,,, and,,,,,tracking,,,,,the,,,,,carrier,,,,,precisely,,,,,is,,,,,the,,,,,foundation,,,,,of,,,,,system,,,,, ,so,,,,,some,,,,,special,,,,,problem,,,,,needs,,,,,to,,,,,be,,,,,solved.,,,,,In,,,,,the,,,,,hybrid,,,, ,DS/FHSS,,,,,TT&C,,,,,system,,,,,,even,,,,,the,,,,,received,,,,,signal,,,,,has,,,,,been,,,,,de hopped,,,,,by,,,,,the,,,,,pattern,,,,,synchronization,,,,,module,,,,,,due,,,,,to,,,,,the,,,,,Dopp ler,,,,,Effect,,,,,and,,,,,carrier,,,,,frequency,,,,,hopping,,,,,,the,,,,,input,,,,,frequency,,,,,of, ,,,,tracking,,,,,loop,,,,,contains,,,,,frequency,,,,,agility,,,,,severely.,,,,,As,,,,,a,,,,,result,,,,,, the,,,,,loop,,,,,is,,,,,likely,,,,,to,,,,,shift,,,,,to,,,,,the,,,,,frequency,,,,,step,,,,,responses,,,,,state,,,,,again,,,,,and,,,,,again,,,,,,and,,,,,it,,,,,seems,,,,,to,,,,,be,,,,,impossible,,,,,for,,,,,freq uency,,,,,measurement,,,,,and,,,,,carrier,,,,,tracking.,,,,,,,,,,The,,,,,paper,,,,,is,,,,,organize d,,,,,as,,,,,follows.,,,,,In,,,,,section,,,,,I,,,,,,the,,,,,frequency,,,,,hopping,,,,,pattern,,,,,sync hronization,,,,,module,,,,,in,,,,,the,,,,,DS/FHSS,,,,,TT&C,,,,,system,,,,,is,,,,,introduced., ,,,,In,,,,,section,,,,,II,,,,,,we,,,,,analyze,,,,,how,,,,,the,,,,,carrier,,,,,frequency,,,,,hopping,,, ,,influences,,,,,the,,,,,performance,,,,,of,,,,,the,,,,,carrier,,,,,tracking,,,,,loop.,,,,,In,,,,,sect ion,,,,,III,,,,,,a,,,,,carrier,,,,,tracking,,,,,loop,,,,,aided,,,,,by,,,,,frequency,,,,,hopping,,,,,pat tern,,,,,and,,,,,current,,,,,spacecraft,,,,,velocity,,,,,is,,,,,proposed.,,,,,In,,,,,section,,,,,IV,,,, ,,a,,,,,simulation,,,,,mode,,,,,on,,,,,the,,,,,ground,,,,,of,,,,,actual,,,,,requirement,,,,,of,,,,,T T&C,,,,,system,,,,,is,,,,,built,,,,,and,,,,,the,,,,,results,,,,,of,,,,,simulation,,,,,show,,,,,that,,, ,,this,,,,,method,,,,,is,,,,,very,,,,,simple,,,,,and,,,,,effective,,,,,for,,,,,DS/FHSS,,,,,TT&C,, ,,,system.,,,,,Finally,,,,,,some,,,,,conclusions,,,,,are,,,,,drawn,,,,,in,,,,,section,,,,,V.II．INPUT,,,,,SIGNAL,,,,,OF,,,,,CARRIER,,,,,TRACKING,,,,,LOOPAs,,,,,the,,,,,traditional,,,,,TT&C,,,,,and,,,,,communication,,,,,system,,,,,,the,,,,,inp ut,,,,,signal,,,,,of,,,,,carrier,,,,,tracking,,,,,loop,,,,,must,,,,,be,,,,,a,,,,,monotonous,,,,,inter mediate,,,,,frequency,,,,,signal,,,,,,so,,,,,the,,,,,received,,,,,RF,,,,,signal,,,,,should,,,,,be,,,, ,dehopped,,,,,by,,,,,the,,,,,frequency,,,,,hopping,,,,,patternsynchronization,,,,,module.,,,, ,In,,,,,FH,,,,,communication,,,,,system,,,,,,the,,,,,signal,,,,,during,,,,,a,,,,,hop,,,,,dwell,,,,, time,,,,,is,,,,,a,,,,,narrowband,,,,,signal,,,,,and,,,,,the,,,,,general,,,,,power,,,,,detector,,,,,is ,,,,,commonly,,,,,used,,,,,to,,,,,detect,,,,,the,,,,,frequency,,,,,hopping,,,,,signal,,,,,[2].,,,,,B ut,,,,,in,,,,,the,,,,,hybrid,,,,,DS/FHSS,,,,,TT&C,,,,,system,,,,,,the,,,,,signal,,,,,is,,,,,subme rged,,,,,in,,,,,the,,,,,noise,,,,,,it,,,,,is,,,,,impossible,,,,,to,,,,,acquire,,,,,signal,,,,,directly,,,,, by,,,,,power,,,,,detector,,,,,such,,,,,as,,,,,FH,,,,,communication,,,,,system.,,,,,However,,,, ,,the,,,,,signal,,,,,during,,,,,a,,,,,hop,,,,,dwell,,,,,time,,,,,in,,,,,the,,,,,system,,,,,just,,,,,is,,,,, a,,,,,direct,,,,,sequence,,,,,spread,,,,,spectrum,,,,,signal,,,,,,so,,,,,we,,,,,can,,,,,acquire,,,,,i t,,,,,based,,,,,on,,,,,the,,,,,acquisition,,,,,of,,,,,direct,,,,,sequence,,,,,spread,,,,,spectrum,,,, ,signal.,,,,,The,,,,,acquisition,,,,,methods,,,,,,such,,,,,as,,,,,serial-search,,,,,acquisition,,,,, ,parallel,,,,,acquisition,,,,,and,,,,,rapid,,,,,acquisition,,,,,based,,,,,on,,,,,FFT,,,,,have,,,,,be en,,,,,discussed,,,,,in,,,,,a,,,,,lot,,,,,of,,,,,papers,,,,,[3-5],,,,,,so,,,,,we,,,,,won’t,,,,,discuss,,, ,,the,,,,,problem,,,,,detailedly,,,,,in,,,,,this,,,,,paper.,,,,,In,,,,,our,,,,,system,,,,,,since,,,,,one,,,,,hop,,,,,dwell,,,,,time,,,,,is,,,,,very,,,,,short,,,,,,the,,,,,rapid,,,,,acquisition,,,,,based,,,,, on,,,,,FFT,,,,,which,,,,,can,,,,,extract,,,,,the,,,,,phase,,,,,delay,,,,,and,,,,,carrier,,,,,frequen cy,,,,,at,,,,,one,,,,,time,,,,,will,,,,,be,,,,,the,,,,,best,,,,,way,,,,,for,,,,,acquisition.,,,,,The,,,,,s cheme,,,,,of,,,,,the,,,,,frequency,,,,,hopping,,,,,patters,,,,,acquisition,,,,,,i.e.,,,,,,coarse,,,,, synchronization,,,,,,could,,,,,be,,,,,shown,,,,,as,,,,,Fig,,,,,1.Figure,,,,,1.,,,,,Scheme,,,,,of,,,,,frequency,,,,,hopping,,,,,pattern,,,,,synchronizationThe,,,,,synchronization,,,,,of,,,,,frequency,,,,,hopping,,,,,pattern,,,,,is,,,,,realized,,,,, by,,,,,the,,,,,local,,,,,frequency,,,,,synthesizer,,,,,rapid,,,,,searching,,,,,and,,,,,the,,,,,two,,, ,,dimension,,,,,rapid,,,,,acquisition,,,,,of,,,,,Direct,,,,,Sequence,,,,,PN,,,,,code,,,,,phase,,, ,,and,,,,,carrier,,,,,frequency.,,,,,At,,,,,the,,,,,beginning,,,,,,the,,,,,link,,,,,switch,,,,,is,,,,,o n,,,,,the,,,,,location,,,,,1,,,,,,and,,,,,the,,,,,output,,,,,signal,,,,,of,,,,,local,,,,,frequency,,,,,s ynthesizer,,,,,with,,,,,higher,,,,,hop,,,,,speed,,,,,than,,,,,the,,,,,received,,,,,one,,,,,is,,,,,mi xed,,,,,with,,,,,the,,,,,received,,,,,signal.,,,,,Then,,,,,,via,,,,,the,,,,,band,,,,,pass,,,,,filter,,,,, ,the,,,,,output,,,,,signal,,,,,of,,,,,mixer,,,,,is,,,,,fed,,,,,into,,,,,the,,,,,acquisition,,,,,module, ,,,,of,,,,,PN,,,,,code,,,,,and,,,,,carrier.,,,,,If,,,,,the,,,,,output,,,,,of,,,,,correlator,,,,,in,,,,,acq uisition,,,,,module,,,,,is,,,,,less,,,,,than,,,,,the,,,,,preset,,,,,threshold,,,,,,the,,,,,direct,,,,,se quence,,,,,spread,,,,,spectrum,,,,,signal,,,,,is,,,,,not,,,,,acquired,,,,,during,,,,,this,,,,,hop,,, ,,dwell,,,,,time,,,,,and,,,,,the,,,,,local,,,,,frequency,,,,,synthesizer,,,,,steps,,,,,the,,,,,next,,, ,,frequency.,,,,,By,,,,,contrast,,,,,,if,,,,,detection,,,,,variable,,,,,of,,,,,acquisition,,,,,modul e,,,,,is,,,,,more,,,,,than,,,,,the,,,,,preset,,,,,threshold,,,,,,it,,,,,means,,,,,that,,,,,the,,,,,freque ncy,,,,,hopping,,,,,signal,,,,,is,,,,,acquired,,,,,and,,,,,the,,,,,mixer,,,,,outputs,,,,,a,,,,,stable, ,,,,district,,,,,spread,,,,,spectrum,,,,,signal.,,,,,After,,,,,that,,,,,,the,,,,,switch,,,,,is,,,,,on,,,,, the,,,,,location,,,,,2,,,,,and,,,,,the,,,,,local,,,,,frequency,,,,,synthesizer,,,,,will,,,,,timely,,,,, change,,,,,the,,,,,output,,,,,frequency,,,,,according,,,,,to,,,,,the,,,,,frequency,,,,,hopping,,, ,,pattern.,,,,,After,,,,,the,,,,,coarse,,,,,synchronization,,,,,mentioned,,,,,above,,,,,,the,,,,,D S/FHSS,,,,,signal,,,,,have,,,,,being,,,,,dehopped,,,,,is,,,,,fed,,,,,to,,,,,PN,,,,,code,,,,,tracking,,,,,loop,,,,,and,,,,,a,,,,,fine,,,,,alignment,,,,,between,,,,,the,,,,,received,,,,,PN,,,,,code,,,,,and,,,,,local,,,,,PN,,,,,code,,,,,is,,,,,achieved,,,,,by ,,,,,a,,,,,code,,,,,tracking,,,,,loop,,,,,na mely ,,,,,the,,,,,delay-locked,,,,,loop.,,,,,Then,,,,,,the,,,,,output,,,,,of,,,,,code,,,,,tracking,,,,,loop,,,,,,i.e.,,,,,,a,,,,,duplicate,,,,,of,,,,,received,,,,,PN,,,,,code,,,,,,is,,,,,mixed,,,,,to,,,,,th e,,,,,IF,,,,,direct,,,,,sequence,,,,,spread,,,,,spectrum,,,,,signal,,,,,dehopped,,,,,by ,,,,,coarse ,,,,,synchronization,,,,,,and,,,,,a,,,,,monotonous,,,,,intermediate,,,,,frequency ,,,,,narrowb and,,,,,,,,,,signal,,,,,which,,,,,will,,,,,be,,,,,fed,,,,,to,,,,,carrier,,,,,tracking,,,,,loop,,,,,is,,,,,o btained.III.,,,,,CHARACTERISTIC,,,,,OF,,,,,DS/FHSS,,,,,CARRIER,,,,,TRA CKING,,,,,LOOPCompared,,,,,with,,,,,the,,,,,carrier,,,,,tracking,,,,,loop,,,,,in,,,,,ordinarycommunica tion,,,,,system,,,,,,because,,,,,of,,,,,the,,,,,high,,,,,dynamic,,,,,of,,,,,the,,,,,spacecraft,,,,,,e specially,,,,,during,,,,,the,,,,,landing,,,,,,accelerating,,,,,and,,,,,decelerating,,,,,,the,,,,,car rier,,,,,tracking,,,,,loop,,,,,of,,,,,hybrid,,,,,DS/FHSS,,,,,TT&C,,,,,system,,,,,will,,,,,be,,,,,i nfluenced,,,,,more,,,,,severely ,,,,,by,,,,,the,,,,,Doppler,,,,,Effect,,,,,(up,,,,,to,,,,,100KHz).,,,,,Addition,,,,,to,,,,,that,,,,,,a,,,,,Doppler,,,,,frequency ,,,,,agility ,,,,,resulted,,,,,from,,,,,th e,,,,,carrier,,,,,frequency ,,,,,hopping,,,,,won’t,,,,,be,,,,,eliminated,,,,,by ,,,,,dehopping,,,,,t he,,,,,frequency ,,,,,hopping,,,,,carrier,,,,,,and,,,,,which,,,,,becomes,,,,,the,,,,,main,,,,,fact or,,,,,influencing,,,,,the,,,,,performance,,,,,of,,,,,carrier,,,,,tracking,,,,,loop,,,,,in,,,,,DS/F HSS,,,,,TT&C,,,,,system.,,,,,The,,,,,frequency ,,,,,of,,,,,downlink,,,,,signal,,,,,of,,,,,DS/F HSS,,,,,TT&C,,,,,system,,,,,may ,,,,,be,,,,,described,,,,,as:)()(1)()()()(000i v i f c i f i f i f i f d +=+= where,,,,,i,,,,,is,,,,,the,,,,,sequence,,,,,number,,,,,of,,,,,carrier,,,,,frequency ,,,,,,)(0i f is,,,,,the,,,,,,,,,,ith,,,,,carrier,,,,,frequency ,,,,,,,,,,,)(i f d is,,,,,the,,,,,Doppler,,,,,frequency ,,,,,offset,,,,,during,,,,,the,,,,,,,,,,ith,,,,,hop,,,,,dwell,,,,,time,,,,,and,,,,,,,,,,)(i v ,,,,,is,,,,,the,,,,,current,,,,,speed,,,,,of,,,,,spacecraft.,,,,,We,,,,,can,,,,,assume,,,,,that,,,,,the,,,,,synchroniz ation,,,,,of,,,,,frequency ,,,,,hopping,,,,,pattern,,,,,has,,,,,been,,,,,completed,,,,,,and,,,,,the,,,,,output,,,,,frequency ,,,,,of,,,,,local,,,,,frequency ,,,,,synthesizer,,,,,is)()()(i f i f i f o lo ∆-=,,,,,,,,,,,where,,,,,)(i f ∆is,,,,,the,,,,,frequency ,,,,,difference,,,,,between,,,,,the,,,,,received,,,,,and,,,,,local,,,,,frequency ,,,,,,i.e.,,,,,,the,,,,,intermediate,,,,,freque ncy ,,,,,of,,,,,input,,,,,signal,,,,,of,,,,,carrier,,,,,tracking,,,,,loop.,,,,,Passing,,,,,a,,,,,IF,,,,,ba nd,,,,,pass,,,,,filter,,,,,,a,,,,,IF,,,,,signal,,,,,,the,,,,,frequency ,,,,,of,,,,,which,,,,,is,,,,,)(i f ∆,,,,,,is,,,,,obtained.,,,,,According,,,,,to,,,,,the,,,,,relation,,,,,among,,,,,the,,,,,velocity ,,,,,,carrier,,,,,frequen cy ,,,,,and,,,,,Doppler,,,,,frequency ,,,,,offset,,,,,,the,,,,,input,,,,,frequency ,,,,,of,,,,,carrier,,,,,tracking,,,,,loop,,,,,is,,,,,derived,,,,,easily,,,,,as,,,,,follow:,,,,,)()(1)()()()(0i v i f c i f i f i f i f d in +=+=∆∆ Then,,,,,,between,,,,,the,,,,,interval,,,,,of,,,,,the,,,,,,,,,,ith,,,,,frequency ,,,,,and,,,,,the,,,,,(i+i)th,,,,,frequency ,,,,,,the,,,,,Doppler,,,,,frequency ,,,,,agility ,,,,,)(i f d ∆,,,,,is,,,,,genera ted,,,,,,and,,,,,can,,,,,be,,,,,expressed,,,,,as:,,,,,)]()()1()1([1)(00i v i f i v i f c i f d -++=∆ Generally,,,,,speaking,,,,,,we,,,,,assume,,,,,that,,,,,the,,,,,velocity ,,,,,of,,,,,spacecraft ,,,,,during,,,,,two,,,,,adjacent,,,,,frequency ,,,,,won’t,,,,,change,,,,,,i.e.)()1(i v i v =+,,,,,,s o )()(1)(0i f i v ci f d ∆∆=,,,,,,which,,,,,shows,,,,,,,,,,that,,,,,the,,,,,frequency,,,,,agility,,,,,is,,,,,a,,,,,function,,,,,of,,,,,the,,,,,frequency ,,,,,difference,,,,,of,,,,,two,,,,,adjacent,,,,,hop,,,,,a nd,,,,,the,,,,,current,,,,,speed,,,,,of,,,,,spacecraft.,,,,,,,,,,Then,,,,,,the,,,,,input,,,,,signal,,,,,of,,,,,the,,,,,carrier,,,,,tracking,,,,,loop,,,,,can,,,,,be ,,,,,expressed,,,,,as:,,,,,,,,,, )(])()()(1222sin[)(2)(0t n nT t p n f n v c t f t f t R P t s n ab +++-++∙=∑∞∞→∆∆τσπππ where,,,,,P,,,,,is,,,,,the,,,,,carrier,,,,,power,,,,,after,,,,,the,,,,,synchronization,,,,,of,,,,,freq uency ,,,,,hopping,,,,,pattern,,,,,,)(t R ,,,,,is,,,,,the,,,,,modulated,,,,,data,,,,,,∆f ,,,,,is,,,,,the,,,,,intermediate,,,,,frequency ,,,,,,d f and,,,,,τ,,,,,are,,,,,the,,,,,rudimental,,,,,frequency ,,,,,o ffset,,,,,and,,,,,rudimental,,,,,phase,,,,,offset,,,,,brought,,,,,from,,,,,acquisition,,,,,module ,,,,,respective.,,,,,;1)(,10=≤≤t p t otherwise,,,,,0)(=t p ,,,,,,T,,,,,is,,,,,one,,,,,hop,,,,,dw ell,,,,,time,,,,,,σ,,,,,,,,,,is,,,,,the,,,,,timing,,,,,error,,,,,of,,,,,the,,,,,synchronization,,,,,of,,,,,f requency ,,,,,hopping,,,,,patterns,,,,,,n(t),,,,,is,,,,,the,,,,,additive,,,,,white,,,,,Gaussian,,,,,noise,,,,,with,,,,,two-side,,,,,power,,,,,spectral,,,,,density ,,,,,2N W/Hz,,,,,and,,,,,c,,,,,is,,,,,t he,,,,,velocity ,,,,,of,,,,,light.,,,,,The,,,,,tracking,,,,,resolution,,,,,is,,,,,the,,,,,basic,,,,,description,,,,,of,,,,,the,,,,,loop,,,,,performance,,,,,,and,,,,,we,,,,,can,,,,,obtain,,,,,it,,,,,by ,,,,,the,,,,,error,,,,,transfer,,,,,fun ction,,,,,as,,,,,follow:,,,,,where,,,,,,F(s),,,,,is,,,,,the,,,,,transfer,,,,,function,,,,,of,,,,,loop,,,,,filter,,,,,,K,,,,,is,,,,,the,,,,,gain,,,,,of,,,,,open,,,,,loop.,,,,,Then,,,,,we,,,,,can,,,,,apply,,,,,the,,,,,limit,,,,,theorem,,,,,,which,,,,,is,,,,,expressed,,,,,as,,,,,)()()(0100lim s H s s s Θ=∞→θ,to,,,,,derive,,,,,the,,,,,steady-state,,,,,tracking,,,,,error.,,,,,Unfortunately ,,,,,,the,,,,,derivation,,,,,of,,,,,Laplacian,,,,,transfer,,,,,of,,,,,,,,,,is,,,,,seen,,,,,to,,,,,be,,,,,impossible,,,,,,so,,,,,we,,,,,can’t,,,,,calcula te,,,,,the,,,,,measuring,,,,,error,,,,,precisely ,,,,,and,,,,,only,,,,,analyze,,,,,it,,,,,by ,,,,,simula tion.,,,,,For,,,,,the,,,,,2edorder,,,,,loop,,,,,,the,,,,,acquisition,,,,,time,,,,,can,,,,,be,,,,,expre ssed,,,,,as:3202nT ξωωρ∆= where,,,,,,0ω,,,,,is,,,,,the,,,,,initial,,,,,frequency ,,,,,offset,,,,,,n ω,,,,,and,,,,,ξ,,,,,are,,,,,the,,,,,natural,,,,,frequency ,,,,,and,,,,,damping,,,,,factor,,,,,of,,,,,the,,,,,tracking,,,,,loop.,,,,,In,,,,,the,,,,,hybrid,,,,,DS/FHSS,,,,,TT&C,,,,,system,,,,,,0ω,,,,,just,,,,,is,,,,,the,,,,,freque ncy ,,,,,agility ,,,,,which,,,,,is,,,,,a,,,,,function,,,,,of,,,,,time,,,,,according,,,,,to,,,,,the,,,,,fre quency ,,,,,hopping,,,,,pattern.,,,,,Thereby ,,,,,,three,,,,,cases,,,,,are,,,,,discussed.,,,,,Case,,,,,1:,,,,,Tp<Tc,,,,,,,,,,,i.e.,,,,,,hop,,,,,dwell,,,,,time,,,,,is,,,,,more,,,,,than,,,,,the,,,,,loop,,,,,acquisition,,,,,time.The,,,,,carrier,,,,,tracking,,,,,loop,,,,,is,,,,,able,,,,,to,,,,,acqu ire,,,,,and,,,,,track,,,,,the,,,,,DS/FHSS,,,,,TT&C,,,,,signal,,,,,,but,,,,,shift,,,,,the,,,,,unlock ,,,,,state,,,,,immediately ,,,,,when,,,,,the,,,,,next,,,,,frequency ,,,,,signal,,,,,is,,,,,fed,,,,,to,,,,,the,,,,,loop.,,,,,The,,,,,loop,,,,,steps,,,,,to,,,,,lock,,,,,,unlock,,,,,,re-lock,,,,,,re-unlock,,,,,s tate,,,,,repeatedly,,,,,for,,,,,all,,,,,time,,,,,,and,,,,,the,,,,,Doppler,,,,,offset,,,,,can’t,,,,,be,,,,,extracted,,,,,accurately .Case,,,,,2:,,,,,Tp>Tc,,,,,,i.e.,,,,,,hop,,,,,dwell,,,,,time,,,,,is,,,,,less,,,,,than,,,,,the,,,,,lo op,,,,,acquisition,,,,,time.,,,,,During,,,,,the,,,,,acquisition,,,,,state,,,,,of,,,,,loop,,,,,,the,,,,,f requency ,,,,,of,,,,,input,,,,,signal,,,,,is,,,,,likely ,,,,,to,,,,,step,,,,,up,,,,,suddenly ,,,,,,and,,,,,t hen,,,,,the,,,,,loop,,,,,steps,,,,,to,,,,,the,,,,,acquisition,,,,,state,,,,,once,,,,,again.,,,,,For,,,,,t he,,,,,case,,,,,,the,,,,,tracking,,,,,loop,,,,,will,,,,,step,,,,,to,,,,,acquisition,,,,,state,,,,,again,,,,,and,,,,,again,,,,,for,,,,,all,,,,,time.,,,,,,,,,,Case,,,,,3:,,,,,For,,,,,the,,,,,non-ideal,,,,,2ed,,,,,or,,,,,high-degree,,,,,order,,,,,loop,,,,,,the,,,,,acquisition,,,,,band,,,,,p ω∆,,,,,is,,,,,limited,,,,,,and,,,,,the,,,,,hopping,,,,,frequenc y ,,,,,agility,,,,,)(i f d ∆,,,,,also,,,,,influences,,,,,the,,,,,performance,,,,,of,,,,,loop.,,,,,When )(i f d ∆<p ω∆,,,,,,,,,,,the,,,,,conclusion,,,,,is,,,,,same,,,,,as,,,,,the,,,,,analysis,,,,,,,,,,mentio ned,,,,,above,,,,,,and,,,,,when )(i f d ∆>p ω∆,,,,,,,,,,,the,,,,,tracking,,,,,loop,,,,,won’t,,,,,loc ked,,,,,the,,,,,signal,,,,,forever.The,,,,,simulation,,,,,result,,,,,of,,,,,2ed,,,,,order,,,,,tracking,,,,,loop,,,,,used,,,,,com monly,,,,,in,,,,,TT&C,,,,,field,,,,,is,,,,,shown,,,,,in,,,,,Fig,,,,,2.,,,,,The,,,,,Doppler,,,,,agilit y ,,,,,is,,,,,plotted,,,,,by ,,,,,broken,,,,,line,,,,,and,,,,,the,,,,,time,,,,,response,,,,,is,,,,,denoted ,,,,,by ,,,,,real,,,,,line.,,,,,Fig.,,,,,2(a),,,,,shows,,,,,the,,,,,tracking,,,,,performance,,,,,witho ut,,,,,Doppler,,,,,offset,,,,,agility;,,,,,the,,,,,time,,,,,response,,,,,as,,,,,Tp<Tc,,,,,is,,,,,descr ibed,,,,,in,,,,,Fig.,,,,,2(b),,,,,,the,,,,,loop,,,,,state,,,,,is,,,,,alternating,,,,,between,,,,,locked,,,,,and,,,,,,,,,,unlocked.,,,,,In,,,,,Fig.,,,,,2(c),,,,,,the,,,,,loop,,,,,is,,,,,acquiring,,,,,signal,,,,,f orever.,,,,,Because,,,,,the,,,,,frequency ,,,,,is,,,,,changed,,,,,before,,,,,stepping,,,,,to,,,,,the ,,,,,locked,,,,,state,,,,,,the,,,,,loop,,,,,won’t,,,,,acquire,,,,,any ,,,,,signal,,,,,at,,,,,all,,,,,time.,,,,,In,,,,,Fig,,,,,2(d),,,,,,when )(i f d ∆>p ω∆,,,,,,the,,,,,tracking,,,,,capability ,,,,,of,,,,,the,,,,,loop,,,,,is,,,,,invalid,,,,,entirely .Figure,,,,,2.,,,,,Time,,,,,response,,,,,of,,,,,tracking,,,,,loop,,,,,with,,,,,Doppler,,,,,offset,,,,,agility:,,,,,,,,,,,,,,,(a) No,,,,,hopping,,,,,,(b),,,,,Tp<Tc,,,,,,,,,,,,,,,,(c),,,,,Tp>T c,,,,,,(d),,,,,)(i f d ∆>pω∆IV.,,,,,THE,,,,,SCHEME,,,,,OF,,,,,CARRIER,,,,,TRACKING,,,,,LOO P,,,,,AIDED,,,,,BY,,,,,HOPPING,,,,,PA TTERNThe,,,,,structure,,,,,of,,,,,the,,,,,carrier,,,,,track,,,,,loop,,,,,aided,,,,,by,,,,,the,,,,,hoppi ng,,,,,frequency,,,,,pattern,,,,,is,,,,,shown,,,,,in,,,,,Fig,,,,,3.,,,,,Generally,,,,,speaking,,,,,, we,,,,,can,,,,,assume,,,,,that,,,,,the,,,,,velocity,,,,,during,,,,,the,,,,,interval,,,,,time,,,,,betw een,,,,,two,,,,,adjacent,,,,,frequency,,,,,will,,,,,keep,,,,,a,,,,,fixed,,,,,value,,,,,,then,,,,,the,,,,,doppler,,,,,frequency,,,,,offset,,,,,,,,,,in,,,,,the,,,,,next,,,,,frequency,,,,,interval,,,,,c an,,,,,be,,,,,calculated,,,,,by,,,,,the,,,,,current,,,,,velocity,,,,,of,,,,,spacecraft,,,,,combined,,,,,with,,,,,carrier,,,,,frequency.,,,,,The,,,,,is,,,,,added,,,,,timely,,,,,to,,,,,the,,,,,adjust ment,,,,,value,,,,,of,,,,,the,,,,,carrier,,,,,NCO,,,,,when,,,,,the,,,,,new,,,,,frequency,,,,,signa l,,,,,is,,,,,fed,,,,,to,,,,,the,,,,,loop.,,,,,So,,,,,the,,,,,output,,,,,frequency,,,,,of,,,,,NCO,,,,,also ,,,,,changes,,,,,synchronal,,,,,as,,,,,the,,,,,frequency,,,,,changing,,,,,of,,,,,input,,,,,signal,,, ,,,and,,,,,the,,,,,loop,,,,,keeps,,,,,stable.,,,,,Deserve,,,,,to,,,,,mentioned,,,,,,before,,,,,the,,,, ,loop,,,,,stepped,,,,,to,,,,,steady,,,,,state,,,,,,the,,,,,spacecraft,,,,,velocity,,,,,used,,,,,by,,,,,t he,,,,,scheme,,,,,is,,,,,given,,,,,from,,,,,the,,,,,acquisition,,,,,module.,,,,,After,,,,,having,,, ,,being,,,,,locked,,,,,state,,,,,,then,,,,,the,,,,,velocity,,,,,should,,,,,be,,,,,extracted,,,,,from,, ,,,the,,,,,loop,,,,,itself,,,,,directly.,,,,,By,,,,,this,,,,,way,,,,,,the,,,,,loop,,,,,is,,,,,able,,,,,to,,,,, keep,,,,,stable,,,,,even,,,,,on,,,,,the,,,,,high,,,,,dynamic,,,,,condition.,,,,,Figure,,,,,3.,,,,,Carrier,,,,,tracking,,,,,loop,,,,,aided,,,,,by,,,,,frequency,,,,,hopping,,,,,patternBesides,,,,,the,,,,,thermal,,,,,noise,,,,,jitter,,,,,,the,,,,,main,,,,,error,,,,,of,,,,,carrier,,,, ,tracking,,,,,loop,,,,,aided,,,,,by,,,,,the,,,,,frequency,,,,,hopping,,,,,pattern,,,,,is,,,,,the,,,,,f requency,,,,,jitter,,,,,of,,,,,the,,,,,frequency,,,,,synthesizer,,,,,and,,,,,timing,,,,,error,,,,,due ,,,,,to,,,,,frequency,,,,,pattern,,,,,synchronization.,,,,,The,,,,,former,,,,,one,,,,,depends,,,,, on,,,,,the,,,,,resolution,,,,,of,,,,,frequency,,,,,synthesizer,,,,,as,,,,,other,,,,,communication,,,,,and,,,,,we,,,,,only,,,,,discuss,,,,,the,,,,,latter,,,,,one.,,,,,Briefly,,,,,,when,,,,,the,,,,,local, ,,,,frequency,,,,,changing,,,,,of,,,,,the,,,,,local,,,,,frequency,,,,,synthesizer,,,,,is,,,,,advanc ed,,,,,or,,,,,retarded,,,,,to,,,,,the,,,,,one,,,,,of,,,,,receive,,,,,signal,,,,,,the,,,,,aiding,,,,,modu le,,,,,will,,,,,provide,,,,,a,,,,,frequency,,,,,offset,,,,,to,,,,,the,,,,,carrier,,,,,NCO,,,,,at,,,,,the, ,,,,wrong,,,,,time,,,,,and,,,,,the,,,,,loop,,,,,will,,,,,step,,,,,to,,,,,the,,,,,unlocked,,,,,state,,,,, at,,,,,once,,,,,,i.e.,,,,,,response,,,,,of,,,,,frequency,,,,,step.,,,,,Fortunately,,,,,,when,,,,,the,, ,,,frequency,,,,,of,,,,,input,,,,,signal,,,,,changes,,,,,actually,,,,,,the,,,,,loop,,,,,will,,,,,retur n,,,,,to,,,,,the,,,,,steady,,,,,state,,,,,rapidly.,,,,,But,,,,,as,,,,,the,,,,,increase,,,,,of,,,,,synchro nization,,,,,error,,,,,,it,,,,,also,,,,,be,,,,,likely,,,,,to,,,,,become,,,,,too,,,,,severe,,,,,to,,,,,me et,,,,,the,,,,,resolution,,,,,requirement,,,,,of,,,,,the,,,,,TT&C,,,,,system.V.,,,,,SIMULA TIOMThe,,,,,model,,,,,of,,,,,carrier,,,,,tracking,,,,,loop,,,,,of,,,,,hybrid,,,,,DS/FHSS,,,,,sys tem,,,,,is,,,,,shown,,,,,in,,,,,Fig,,,,,3,,,,,,which,,,,,is,,,,,built,,,,,in,,,,,the,,,,,simulink,,,,,of,, ,,,Matlab.,,,,,The,,,,,tracking,,,,,loop,,,,,is,,,,,the,,,,,standard,,,,,costas,,,,,loop,,,,,commo nly,,,,,used,,,,,in,,,,,the,,,,,TT&C,,,,,field,,,,,,which,,,,,is,,,,,able,,,,,to,,,,,eliminate,,,,,the,, ,,,inference,,,,,resulted,,,,,form,,,,,the,,,,,polarity,,,,,change,,,,,of,,,,,the,,,,,modulated,,,,, data,,,,,[9].,,,,,To,,,,,adapt,,,,,the,,,,,Doppler,,,,,frequency,,,,,change,,,,,due,,,,,to,,,,,the,,,, ,spacecraft,,,,,movement,,,,,,the,,,,,loop,,,,,is,,,,,designed,,,,,as,,,,,a,,,,,2ed,,,,,order,,,,,loo p,,,,,,and,,,,,the,,,,,loop,,,,,filter,,,,,is,,,,,a,,,,,1st,,,,,order,,,,,filter.,,,,,The,,,,,simulation,,,,, parameter,,,,,is,,,,,set,,,,,according,,,,,to,,,,,the,,,,,actual,,,,,TT&C,,,,,task,,,,,as,,,,,follow s:,,,,,Carrier,,,,,frequency:,,,,,2.2GHz~2.3GHz,,,,,Amount,,,,,of,,,,,frequencies:,,,,,128,,,,,Frequency,,,,,hopping,,,,,pattern:,,,,,based,,,,,on,,,,,m-sequence,,,,,Rudimental,,,,,frequency,,,,,offset,,,,,after,,,,,acquisition:,,,,,300Hz,,,,,Intermediate,,,,,frequency,,,,,of,,,,,the,,,,,carrier,,,,,tracking,,,,,loop:,,,,,4.8MHz,,,,,Sampling,,,,,frequency:,,,,,16.3Mbps,,,,,Noise,,,,,Bandwidth,,,,,of,,,,,the,,,,,loop:,,,,,10Hz,,,,,A.,,,,,The,,,,,time,,,,,response,,,,,on,,,,,uniform,,,,,motion,,,,,and,,,,,,,,,,uniformly,,,, ,accelerated,,,,,motionWe,,,,,assume,,,,,the,,,,,spacecraft,,,,,speed,,,,,is,,,,,7.9km/s,,,,,,by,,,,,the,,,,,relation ,,,,,among,,,,,the,,,,,Doppler,,,,,frequency,,,,,,carrier,,,,,frequency,,,,,and,,,,,velocity,,,,,,t he,,,,,frequency,,,,,offset,,,,,of,,,,,the,,,,,input,,,,,IF,,,,,signal,,,,,of,,,,,loop,,,,,is,,,,,obtaine d,,,,,as,,,,,Fig,,,,,4(a).,,,,,The,,,,,max,,,,,frequency,,,,,agility,,,,,is,,,,,up,,,,,to,,,,,2.3KHz.,,, ,,The,,,,,time,,,,,response,,,,,without,,,,,aid,,,,,is,,,,,shown,,,,,in,,,,,the,,,,,Fig,,,,,4(b),,,,,an d,,,,,the,,,,,one,,,,,with,,,,,aid,,,,,by,,,,,hopping,,,,,pattern,,,,,is,,,,,shown,,,,,in,,,,,Fig4(c)., ,,,,The,,,,,results,,,,,show,,,,,that,,,,,the,,,,,loop,,,,,without,,,,,aid,,,,,is,,,,,unlocked,,,,,com pletely,,,,,,while,,,,,the,,,,,one,,,,,with,,,,,aid,,,,,can,,,,,track,,,,,the,,,,,carrier,,,,,accurately .,,,,,When,,,,,the,,,,,spacecraft,,,,,is,,,,,on,,,,,the,,,,,uniformly,,,,,accelerated,,,,,motion,,,,, (the,,,,,initial,,,,,speed,,,,,is,,,,,7.9km/s,,,,,,and,,,,,speed,,,,,accelerator,,,,,is,,,,,30g),,,,,,th e,,,,,time,,,,,response,,,,,is,,,,,shown,,,,,in,,,,,Fig,,,,,5.,,,,,The,,,,,same,,,,,conclusion,,,,,is, ,,,,obtained,,,,,as,,,,,pre-paragraph.,,,,,Figure,,,,,4.,,,,,,,,,,The,,,,,time,,,,,response,,,,,on,,,,,uniform,,,,,,,,,,,,,,,motion:,,,,,(a)doppler,,,,,frequency,(b)without,,,,,aid,,,,,,(c),,,,,with,,,,,aid.Figure,,,,,5.,,,,,Time,,,,,response,,,,,on,,,,,uniformly,,,,,accelerated,,,,,motion:(a)doppler,,,,,frequency,(b)without,,,,,aid,,,,,(c),,,,,with,,,,,aidB.,,,,,Tracking,,,,,resolution,,,,,on,,,,,different,,,,,hopping,,,,,speedIn,,,,,this,,,,,simulation,,,,,,the,,,,,resolution,,,,,of,,,,,carrier,,,,,tracking,,,,,loop,,,,,is, ,,,,obtained,,,,,by,,,,,calculating,,,,,variance.,,,,,The,,,,,relation,,,,,between,,,,,tracking,,,, ,resolution,,,,,and,,,,,hopping,,,,,speed,,,,,is,,,,,shown,,,,,in,,,,,Fig,,,,,6,,,,,on,,,,,different,, ,,,input,,,,,SNR,,,,,and,,,,,the,,,,,minimum,,,,,value,,,,,insuring,,,,,the,,,,,demodulating,,,, ,correctly,,,,,in,,,,,TT&C,,,,,system,,,,,is,,,,,13,,,,,dB.,,,,,The,,,,,result,,,,,of,,,,,simulation ,,,,,testified,,,,,that,,,,,the,,,,,resolution,,,,,is,,,,,not,,,,,sensitive,,,,,to,,,,,the,,,,,hopping,,,,, speed,,,,,and,,,,,the,,,,,scheme,,,,,is,,,,,very,,,,,robust,,,,,for,,,,,different,,,,,hopping,,,,,spe ed.Figure,,,,,6.,,,,,Stead-state,,,,,tracking,,,,,resolution,,,,,vs,,,,,hopping,,,,,speedC.,,,,,Tracking,,,,,resolution,,,,,on,,,,,different,,,,,timing,,,,,error,,,,,of,,,,,frequency, ,,,,,,,,,pattern,,,,,,,,,,synchronization,,,,,,,,,,For,,,,,carrier,,,,,tracking,,,,,loop,,,,,aided,,,,,by,,,,,the,,,,,frequency,,,,,hopping,,,,,p attern,,,,,,according,,,,,to,,,,,the,,,,,above,,,,,discussion,,,,,the,,,,,main,,,,,factor,,,,,impact ing,,,,,the,,,,,stability,,,,,of,,,,,loop,,,,,is,,,,,the,,,,,timing,,,,,error,,,,,caused,,,,,by,,,,,the,,,,, patterns,,,,,synchronization.,,,,,Fig,,,,,7,,,,,shows,,,,,the,,,,,stead-state,,,,,tracking,,,,,acc uracies,,,,,on,,,,,different,,,,,timing,,,,,error,,,,,of,,,,,synchronization,,,,,pattern,,,,,on,,,,,d ifferent,,,,,input,,,,,SNR.,,,,,The,,,,,measuring,,,,,error,,,,,is,,,,,increase,,,,,as,,,,,increasin g,,,,,of,,,,,timing,,,,,error,,,,,and,,,,,the,,,,,measurement,,,,,error,,,,,resulted,,,,,from,,,,,the ,,,,,SNR,,,,,even,,,,,can,,,,,be,,,,,ignored,,,,,when,,,,,the,,,,,time,,,,,error,,,,,is,,,,,up,,,,,to,,, ,,some,,,,,specified,,,,,value.,,,,,Consequently,,,,,,we,,,,,can,,,,,infer,,,,,that,,,,,the,,,,,trac k,,,,,accuracy,,,,,won’t,,,,,meet,,,,,the,,,,,requirement,,,,,of,,,,,TT&C,,,,,system,,,,,finally ,,,,,,and,,,,,the,,,,,problem,,,,,needs,,,,,to,,,,,be,,,,,researched,,,,,in,,,,,the,,,,,future.Figure,,,,,7.,,,,,Stead-state,,,,,tracking,,,,,resolution,,,,,vs,,,,,timing,,,,,error,,,,,of,,,,,,,,,,pattern,,,,,synchronization。

通信类英文文献及翻译

附录一、英文原文：Detecting Anomaly Trafﬁc using Flow Data in the realVoIP networkI. INTRODUCTIONRecently, many SIP[3]/RTP[4]-based VoIP applications and services have appeared and their penetration ratio is gradually increasing due to the free or cheap call charge and the easy subscription method. Thus, some of the subscribers to the PSTN service tend to change their home telephone services to VoIP products. For example, companies in Korea such as LG Dacom, Samsung Net- works, and KT have begun to deploy SIP/RTP-based VoIP services. It is reported that more than ﬁve million users have subscribed the commercial VoIP services and 50% of all the users are joined in 2009 in Korea [1]. According to IDC, it is expected that the number of VoIP users in US will increase to 27 millions in 2009 [2]. Hence, as the VoIP service becomes popular, it is not surprising that a lot of VoIP anomaly trafﬁc has been already known [5]. So, Most commercial service such as VoIP services should provide essential security functions regarding privacy, authentication, integrity and non-repudiation for preventing malicious trafﬁc. Particu- larly, most of current SIP/RTP-based VoIP services supply the minimal security function related with authentication. Though secure transport-layer protocols such as Transport Layer Security (TLS) [6] or Secure RTP (SRTP) [7] have been standardized, they have not been fully implemented anddeployed in current VoIP applications because of the overheads of implementation and performance. Thus, un-encrypted VoIP packets could be easily sniffed and forged, especially in wireless LANs. In spite of authentication,the authentication keys such as MD5 in the SIP header could be maliciously exploited, because SIP is a text-based protocol and unencrypted SIP packets are easily decoded. Therefore, VoIP services are very vulnerable to attacks exploiting SIP and RTP. We aim at proposing a VoIP anomaly trafﬁc detection method using the ﬂow-based trafﬁc measurement archi-tecture. We consider three representative VoIP anomalies called CANCEL, BYE Denial of Service (DoS) and RTP ﬂooding attacks in this paper, because we found that malicious users in wireless LAN could easily perform these attacks in the real VoIP network. For monitoring VoIP packets, we employ the IETF IP Flow Information eXport (IPFIX) [9] standard that is based on NetFlow v9. This trafﬁc measurement method provides a ﬂexible and extensible template structure for various protocols, which is useful for observing SIP/RTP ﬂows [10]. In order to capture and export VoIP packets into IPFIX ﬂows, we deﬁne two additional IPFIX templates for SIP and RTP ﬂows. Furthermore, we add four IPFIX ﬁelds to observe packets which are necessary to detect VoIP source spooﬁng attacks in WLANs.II. RELATED WORK[8] proposed a ﬂooding detection method by the Hellinger Distance (HD) concept. In [8], they have pre- sented INVITE, SYN and RTP ﬂooding detection meth-ods. The HD is the difference value between a training data set and a testing data set. The training data set collected trafﬁc over n sampling period of duration Δ testing data set collected trafﬁc next the training data set in the same period. If the HD is close to ‘1’, this testing data set is regarded as anomaly trafﬁc. For using this method, they assumed that initial training data set didnot have any anomaly trafﬁc. Since this method was based on packet counts, it might not easily extended to detect other anomaly trafﬁc except ﬂooding. On the other hand, [11] has proposed a VoIP anomaly trafﬁc detection method using Extended Finite State Machine (EFSM). [11] has suggested INVITE ﬂooding, BYE DoS anomaly trafﬁc and media spamming detection methods. However, the state machine required more memory because it had to maintain each ﬂow. [13] has presented NetFlow-based VoIP anomaly detection methods for INVITE, REGIS-TER, RTP ﬂooding, and REGISTER/INVITE scan. How-ever, the VoIP DoS attacks considered in this paper were not considered. In [14], an IDS approach to detect SIP anomalies was developed, but only simulation results are presented. For monitoring VoIP trafﬁc, SIPFIX [10] has been proposed as an IPFIX extension. The key ideas of the SIPFIX are application-layer inspection and SDP analysis for carrying media session information. Yet, this paper presents only the possibility of applying SIPFIX to DoS anomaly trafﬁc detection and prevention. We described the preliminary idea of detecting VoIP anomaly trafﬁc in [15]. This paper elaborates BYE DoS anomaly trafﬁc and RTP ﬂooding anomaly trafﬁc detec-tion method based on IPFIX. Based on [15], we have considered SIP and RTP anomaly trafﬁc generated in wireless LAN. In this case, it is possible to generate the similiar anomaly trafﬁc with normal VoIP trafﬁc, because attackers can easily extract normal user information from unencrypted VoIP packets. In this paper, we have extended the idea with additional SIP detection methods using information of wireless LAN packets. Furthermore, we have shown the real experiment results at the commercial VoIP network.III. THE VOIP ANOMALY TRAFFIC DETECTION METHOD A. CANCEL DoS Anomaly Trafﬁc DetectionAs the SIP INVITE message is not usually encrypted, attackers could extract ﬁelds necessary to reproduce the forged SIP CANCEL message by snifﬁng SIP INVITE packets, especially in wireless LANs. Thus, we cannot tell the difference between the normal SIP CANCEL message and the replicated one, because the faked CANCEL packet includes the normal ﬁelds inferred from the SIP INVITE message. The attacker will perform the SIP CANCEL DoS attack at the same wireless LAN, because the purpose of the SIP CANCEL attack is to prevent the normal call estab-lishment when a victim is waiting for calls. Therefore, as soon as the attacker catches a call invitation message for a victim, it will send a SIP CANCEL message, which makes the call establishment failed. We have generated faked SIP CANCEL message using sniffed a SIP INVITE in SIP header of this CANCEL message is the same as normal SIP CANCEL message, because the attacker can obtain the SIP header ﬁeld from unencrypted normal SIP message in wireless LAN environment. Therefore it is impossible to detect the CANCEL DoS anomaly trafﬁc using SIP headers, we use the different values of the wireless LAN frame. That is, the sequence number in the frame will tell the difference between a victim host and an attacker. We look into source MAC address and sequence number in the MAC frame including a SIP CANCEL message as shown in Algorithm 1. We compare the source MAC address of SIP CANCEL packets with that of the previously saved SIP INVITE ﬂow. If the source MAC address of a SIP CANCEL ﬂow is changed, it will be highly probable that the CANCEL packet is generated by a unknown user. However, the source MAC address could be spoofed. Regarding source spooﬁng detection, we employ the method in [12] that uses sequence numbers of frames. We calculate the gap between n-th and (n-1)-th frames. As the sequence number ﬁeld in a MAC header uses 12 bits, it varies from 0 to 4095. When we ﬁnd that the sequence number gap between a single SIP ﬂow is greater than the threshold value of N that willbe set from the experiments, we determine that the SIP host address as been spoofed for the anomaly trafﬁc.B. BYE DoS Anomaly Trafﬁc DetectionIn commercial VoIP applications, SIP BYE messages use the same authentication ﬁeld is included in the SIP IN-VITE message for security and accounting purposes. How-ever, attackers can reproduce BYE DoS packets through snifﬁng normal SIP INVITE packets in wireless faked SIP BYE message is same with the normal SIP BYE. Therefore, it is difﬁcult to detect the BYE DoS anomaly trafﬁc using only SIP header snifﬁng SIP INVITE message, the attacker at the same or different subnets could terminate the normal in- progress call, because it could succeed in generating a BYE message to the SIP proxy server. In the SIP BYE attack, it is difﬁcult to distinguish from the normal call termination procedure. That is, we apply the timestamp of RTP trafﬁc for detecting the SIP BYE attack. Generally, after normal call termination, the bi-directional RTP ﬂow is terminated in a bref space of time. However, if the call termination procedure is anomaly, we can observe that a directional RTP media ﬂow is still ongoing, whereas an attacked directional RTP ﬂow is broken. Therefore, in order to detect the SIP BYE attack, we decide that we watch a directional RTP ﬂow for a long time threshold of N sec after SIP BYE message. The threshold of N is also set from the 2 explains the procedure to detect BYE DoS anomal trafﬁc using captured timestamp of the RTP packet. We maintain SIP session information between clients with INVITE and OK messages including the same Call-ID and 4-tuple (source/destination IP Address and port number) of the BYE packet. We set a time threshold value by adding Nsec to the timestamp value of the BYE message. The reason why we use the captured timestamp is that a few RTP packets are observed under second. If RTP trafﬁc is observed after the time threshold, this willbe considered as a BYE DoS attack, because the VoIP session will be terminated with normal BYE messages. C. RTP Anomaly Trafﬁc Detection Algorithm 3 describes an RTP ﬂooding detection method that uses SSRC and sequence numbers of the RTP header. During a single RTP session, typically, the same SSRC value is maintained. If SSRC is changed, it is highly probable that anomaly has occurred. In addition, if there is a big sequence number gap between RTP packets, we determine that anomaly RTP trafﬁc has happened. As inspecting every sequence number for a packet is difﬁcult, we calculate the sequence number gap using the ﬁrst, last, maximum and minimum sequence numbers. In the RTP header, the sequence number ﬁeld uses 16 bits from 0 to 65535. When we observe a wide sequence number gap in our algorithm, we consider it as an RTP ﬂooding attack.IV. PERFORMANCE EVALUATIONA. Experiment EnvironmentIn order to detect VoIP anomaly trafﬁc, we established an experimental environment as ﬁgure 1. In this envi-ronment, we employed two VoIP phones with wireless LANs, one attacker, a wireless access router and an IPFIX ﬂow collector. For the realistic performance evaluation, we directly used one of the working VoIP networks deployed in Korea where an 11-digit telephone number (070-XXXX-XXXX) has been assigned to a SIP wireless SIP phones supporting , we could make calls to/from the PSTN or cellular phones. In the wireless access router, we used two wireless LAN cards- one is to support the AP service, and the other is to monitor packets. Moreover, in order to observe VoIP packets in the wireless access router, we modiﬁed nProbe [16], that is an open IPFIX ﬂow generator, to create and export IPFIX ﬂows related with SIP, RTP, and information. As the IPFIX collector, we have modiﬁed libipﬁx so that it could provide the IPFIX ﬂow decoding function for SIP, RTP, and templates. We used MySQL for the ﬂow DB.B. Experimental ResultsIn order to evaluate our proposed algorithms, we gen-erated 1,946 VoIP calls with two commercial SIP phones and a VoIP anomaly trafﬁc generator. Table I showsour experimental results with precision, recall, and F-score that is the harmonic mean of precision and recall. In CANCEL DoS anomaly trafﬁc detection, our algorithm represented a few false negative cases, which was related with the gap threshold of the sequence number in MAC header. The average of the F-score value for detecting the SIP CANCEL anomaly is %.For BYE anomaly tests, we generated 755 BYE mes-sages including 118 BYE DoS anomalies in the exper-iment. The proposed BYE DoS anomaly trafﬁc detec-tion algorithm found 112 anomalies with the F-score of %. If an RTP ﬂow is terminated before the threshold, we regard the anomaly ﬂow as a normal one. In this algorithm, we extract RTP session information from INVITE and OK or session description messages using the same Call-ID of BYE message. It is possible not to capture those packet, resulting in a few false-negative cases. The RTP ﬂooding anomaly trafﬁc detection experiment for 810 RTP sessions resulted in the F score of 98%.The reason of false-positive cases was related with the sequence number in RTP header. If the sequence number of anomaly trafﬁc is overlapped with the range of the normal trafﬁc, our algorithm will consider it as normal trafﬁc.V. CONCLUSIONSWe have proposed a ﬂow-based anomaly trafﬁc detec-tion method against SIP and RTP-based anomaly trafﬁc in this paper. We presented VoIP anomaly trafﬁc detection methods with ﬂow data on the wireless access router. We used the IETF IPFIX standard to monitor SIP/RTP ﬂows passing through wireless access routers, because its template architecture is easily extensible to several protocols. For this purpose, we deﬁned two new IPFIX templates for SIP and RTP trafﬁc and four new IPFIX ﬁelds for trafﬁc. Using these IPFIX ﬂow templates,we proposed CANCEL/BYE DoS and RTP ﬂooding trafﬁc detection algorithms. From experimental results on the working VoIP network in Korea, we showed that our method is able to detect three representative VoIP attacks on SIP phones. In CANCEL/BYE DoS anomaly trafﬁcdetection method, we employed threshold values about time and sequence number gap for classﬁcation of normal and abnormal VoIP packets. This paper has not been mentioned the test result about suitable threshold values. For the future work, we will show the experimental result about evaluation of the threshold values for our detection method.二、英文翻译：交通流数据检测异常在真实的世界中使用的VoIP网络一 .介绍最近,许多SIP[3],[4]基于服务器的VoIP应用和服务出现了,并逐渐增加他们的穿透比及由于自由和廉价的通话费且极易订阅的方法。

通信技术类英文文献

通信技术类英文文献IntroductionIn today’s digital age, communication technology plays a crucial role in connecting people, businesses, and devices. From traditional landline telephones to modern smartphones and internet-based communication platforms, the field of communication technology has witnessed significant advancements. This article aims to explore various aspects of communication technology, including its history, types, applications, and future trends.History of Communication Technology1.Early forms of communication technology–Smoke signals–Carrier pigeons–Semaphore telegraphs2.Invention of the telegraph–Samuel Morse and Morse code–Telegraph lines and the expansion of communication networks 3.Telephone revolution–Alexander Graham Bell and the invention of the telephone–Introduction of telephone exchanges and switchboards4.Birth of wireless communication–Guglielmo Marconi and radio transmission–Wireless telegraphy and its impact on long-distancecommunicationTypes of Communication Technology1.Wired communication technology–Traditional landline telephones–Ethernet cables for internet connectivity–Fiber optic cables for high-speed data transmission2.Wireless communication technology–Radio communication–Cellular networks (2G, 3G, 4G, and 5G)–Satellite communication3.Internet-based communication technology–Email and instant messaging–Voice over Internet Protocol (VoIP)–Video conferencing and online collaboration toolsApplications of Communication Technology1.Personal communication–Mobile phones and smartphones–Social media platforms–Messaging apps2.Business communication–Teleconferencing and virtual meetings–Cloud-based collaboration tools–Customer relationship management (CRM) systems3.Healthcare communication–Telemedicine and remote patient monitoring–Electronic health records (EHR)–Communication systems in hospitals and healthcare facilities munication in education–Online learning platforms–Virtual classrooms and webinars–Educational apps and softwareFuture Trends in Communication Technology1.Internet of Things (IoT)–Interconnected devices and sensors–Smart homes and cities2.5G and beyond–Faster data speeds and lower latency–Enhanced connectivity for autonomous vehicles and IoT devices3.Artificial Intelligence (AI) in communication–Chatbots and virtual assistants–Natural language processing for improved communication4.Blockchain technology in communication–Secure and transparent data exchange–Decentralized communication networksConclusionCommunication technology has evolved significantly over the years, revolutionizing the way we connect and interact. From the early forms of communication to the advent of wireless and internet-based technologies, communication has become faster, more efficient, and accessible to a wider audience. As we look towards the future, emerging trends such as IoT, 5G, AI, and blockchain promise to further transform the field of communication technology, opening up new possibilities and opportunities for individuals, businesses, and society as a whole.。

通信工程外文文献

外文资料和中文翻译外文资料：Review of UMTS1.1 UMTS Network ArchitectureThe European/Japanese 3G standard is referred to as UMTS. UMTS is one of a number of standards ratified by the ITU-T under the umbrella of IMT-2000. It is currently the dominant standard, with the US CDMA2000 standard gaining ground, particularly with operators that have deployed cdmaOne as their 2G technology. At time of writing,Japan is the most advanced in terms of 3G network deployment. The three incumbent operators there have implemented three different technologies: J-Phone is using UMTS,KDDI has a CDMA2000 network, and the largest operator NTT DoCoMo is using a system branded as FOMA (Freedom of Multimedia Access). FOMA is based on the original UMTS proposal, prior to its harmonization and standardization.The UMTS standard is specified as a migration from the second generation GSM standard to UMTS via the General Packet Radio System (GPRS) and Enhanced Data for Global Evolution (EDGE), as shown in Figure. This is a sound rationale since as of April 2003, there were over 847 Million GSM subscribers worldwide1, accounting for68% of the global cellular subscriber figures. The emphasis is on keeping as much ofthe GSM network as possible to operate with the new system.We are now well on the road towards Third Generation (3G), where the network will support all traffic types: voice, video and data, and we should see an eventual explosion in the services available on the mobile device. The driving technology for this is the IP protocol. Many cellular operators are now at a position referred to as 2.5G, with the deployment of GPRS, which introduces an IP backbone into the mobile core network.The diagram below, Figure 2, shows an overview of the key components in a GPRS network, and how it fits into the existing GSM infrastructure.The interface between the SGSN and GGSN is known as the Gn interface and uses the GPRS tunneling protocol (GTP, discussed later). The primary reason for the introduction of this infrastructure is to offer connections to external packet networks, such as the Internet or a corporate Intranet.This brings the IP protocol into the network as a transport between the SGSN and GGSN. This allows data services such as email or web browsing on the mobile device,with users being charged based on volume of data rather than time connected.The dominant standard for delivery of 3G networks and services is the Universal Mobile Telecommunications System, or UMTS. The first deployment of UMTS is the Release ’99 architecture, shown below in Figure 3.In this network, the major change is in the radio access network (RAN) with the introduction of CDMA technology for the air interface, and ATM as a transport in the transmission part. These changes have been introduced principally to support the transport of voice, video and data services on the same network. The core network remains relatively unchanged, with primarily software upgrades. However, the IP protocol pushes further into the network with the RNC now communicating with the 3G SGSN using IP.The next evolution step is the Release 4 architecture, Figure 4. Here, the GSM core is replaced with an IP network infrastructure based around Voice over IP technology.The MSC evolves into two separate components: a Media Gateway (MGW) and an MSC Server (MSS). This essentially breaks apart the roles of connection and connection control. An MSS can handle multiple MGWs, making the network more scaleable.Since there are now a number of IP clouds in the 3G network, it makes sense to merge these together into one IP or IP/ATM backbone (it is likely both options will be available to operators.) This extends IP right across the whole network, all the way to the BTS.This is referred to as the All-IP network, or the Release 5 architecture, as shown in Figure 5. The HLR/VLR/EIR are generalised and referred to as the HLR Subsystem(HSS).Now the last remnants of traditional telecommunications switching are removed, leaving a network operating completely on the IP protocol, and generalised for the transport of many service types. Real-time services are supported through the introduction of a new network domain, the IP Multimedia Subsystem (IMS).Currently the 3GPP are working on Release 6, which purports to cover all aspects not addressed in frozen releases. Some call UMTS Release 6 4G and it includes such issues as interworking of hot spot radio access technologies such as wireless LAN.1.2 UMTS FDD and TDDLike any CDMA system, UMTS needs a wide frequency band in which to operate to effectively spread signals. The defining characteristic of the system is the chip rate, where a chip is the width of one symbol of the CDMA code. UMTS uses a chip rate of 3.84Mchips/s and this converts to a required spectrum carrier of 5MHz wide. Since this is wider than the 1.25MHz needed for the existing cdmaOne system, the UMTS air interface is termed ‘wideband’ CDMA.There are actually two radio technologies under the UMTS umbrella: UMTS FDD and TDD. FDD stands for Frequency Division Duplex, and like GSM, separates traffic in the uplink and downlink by placing them at different frequency channels. Therefore an operator must have a pair of frequencies allocated to allow them to run a network, hence the term ‘paired spectrum’. TDD or Time Division Duplex requires only one frequency channel, and uplink and downlink traffic are separated by sending them at different times. The ITU-T spectrum usage, as shown in Figure 6, for FDD is 1920- 980MHz for uplink traffic, and 2110-2170MHz for downlink. The minimum allocation an operator needs is two paired 5MHz channels, one for uplink and one for downlink, at a separation of 190MHz. However, to provide comprehensive coverage and services, it is recommended that an operator be given three channels. Considering the spectrum allocation, there are 12 paired channels available, and many countries have now completed the licencing process for this spectrum, allocating between two and four channels per licence. This has tended to work out a costly process for operators, since the regulatory authorities in some countries, notably in Europe, have auctioned these licences to the highest bidder. This has resulted in spectrum fees as high as tens of billions of dollars in some countries.The Time Division Duplex (TDD) system, which needs only one 5MHz band in which to operate, often referred to as unpaired spectrum. The differences between UMTS FDD and TDD are only evident at the lower layers, particularly on the radio interface. At higher layers, the bulk of the operation of the two systems is the same. As the name suggests, the TDD system separates uplink and downlink traffic by placing them in different time slots. As will be seen later, UMTS uses a 10ms frame structure which is divided into 15 equal timeslots. TDD can allocate these to be either uplink or downlink,with one or more breakpoints between the two in a frame defined. In this way, it is well suited to packet traffic, since this allows great flexibility in dynamically dimensioning for asymmetry in traffic flow.The TDD system should not really be considered as an independent network, but rather as a supplementfor an FDD system to provide hotspot coverage at higher data rates. It is rather unsuitable for large scale deployment due to interference between sites, since a BTS may be trying to detect a weak signal from a UE, which is blocked out by a relatively strong signal at the same frequency from a nearby BTS. TDD is ideal for indoor coverage over small areas.Since FDD is the main access technology being developed currently, the explanations presented here will focus purely on this system.1.3 UMTS Bearer ModelThe procedures of a mobile device connecting to a UMTS network can be split into two areas: the access stratum (AS) and the non-access stratum (NAS). The access stratum involves all the layers and subsystems that offer general services to the non-access stratum. In UMTS, the access stratum consists of all of the elements in the radio access network, including the underlying ATM transport network, and the various mechanisms such as those to provide reliable information exchange. All of the non-access stratum functions are those between the mobile device and the core network, for example, mobility management. Figure 7 shows the architecture model. The AS interacts with the NAS through the use of service access points (SAPs).UMTS radio access network (UTRAN) provides this separation of NAS and AS functions, and allows for AS functions to be fully controlled and implemented within the UTRAN. The two major UTRAN interfaces are the Uu, which is the interface between the mobile device, or User Equipment (UE) and the UTRAN, and the Iu, which is the interface between the UTRAN and the core network. Both of these interfaces can be divided into control and user planes each with appropriate protocol functions.A Bearer Service is a link between two points, which is defined by a certain set of characteristics. In the case of UMTS, the bearer service is delivered using radio access bearers.A Radio access bearer (RAB) is defined as the service that the access stratum (i.e.UTRAN) provides to the non-access stratum for transfer of user data between the User Equipment and Core Network. A RAB can consist of a number of subflows, which are data streams to the core network within the RAB that have different QoS characteristics,such as different reliabilities. A common example of this is different classes of bits with different bit error rates can be realised as different RAB subflows. RAB subflows are established and released at the time the RAB is established and released, and are delivered together over the same transport bearer.A Radio Link is defined as a logical association between a single User Equipment (UE) and a single UTRAN access point, such as an RNC. It is physically comprised of one or more radio bearers and should not be confused with radio access bearer.Looking within the UTRAN, the general architecture model is as shown in Figure 8 below. Now shown are the Node B or Base Station (BTS) and Radio Network Controller (RNC) components, and their respective internal interfaces. The UTRAN is subdivided into blocks referred to as Radio Network Subsystems (RNS), where each RNS consists of one controlling RNC (CRNC) and all the BTSs under its control. Unique to UMTS is the interface between RNSs, the Iur interface, which plays a key role in handover procedures. The interface between the BTS and RNC is the Iub interface.All the ‘I’ interfaces: Iu, Iur and Iub, currently3 use ATM as a transport layer. In the context of ATM, the BTS is seen as a host accessing an ATM network, within which the RNC is an ATM switch. Therefore, the Iub is a UNI interface, whereas the Iu and Iur interfaces are considered to be NNI, as illustrated in Figure 9.This distinction is because the BTS to RNC link is a point-to-point connection in that a BTS or RNC will only communicate with the RNC or BTS directly connected to it, and will not require communication beyond that element to another network element.For each user connection to the core network, there is only one RNC, which maintains the link between the UE and core network domain, as highlighted in Figure 10. This RNC is referred to as the serving RNC or SRNC. That SRNC plus the BTSs under its control is then referred to as the SRNS. This is a logical definition with reference to that UE only. In an RNS, the RNC that controls a BTS is known as the controlling RNC or CRNC. This is with reference to the BTS, cells under its control and all the common and shared channels within.As the UE moves, it may perform a soft or hard handover to another cell. In the case of a soft handover, the SRNC will activate the new connection to the new BTS. Should the new BTS be under the control of another RNC, the SRNC will also alert this new RNC to activate a connection along the Iur interface. The UE now has two links, one directly to the SRNC, and the second, through the new RNC along the Iur interface. In this case, this new RNC is logically referred to as a drift RNC or DRNC, see Figure 10. It is not involved in any processing of the call and merely relays it to the SRNC for connection to the core. In summary, SRNC and DRNC are usually associated with the UE and the CRNC is associated with the BTS. Since these are logical functions it is normal practice that a single RNC is capable of dealing with all these functions.A situation may arise where a UE is connected to a BTS for which the SRNC is not the CRNC for that BTS. In that situation, the network may invoke the Serving RNC Relocation procedure to move the core network connection. This process is described inSection 3.中文翻译：通用移动通信系统的回顾1.1 UMTS网络架构欧洲/日本的3G标准，被称为UMTS。

5G无线通信网络中英文对照外文翻译文献

5G无线通信网络中英文对照外文翻译文献(文档含英文原文和中文翻译)翻译：5G无线通信网络的蜂窝结构和关键技术摘要第四代无线通信系统已经或者即将在许多国家部署。

然而，随着无线移动设备和服务的激增，仍然有一些挑战尤其是4G所不能容纳的，例如像频谱危机和高能量消耗。

无线系统设计师们面临着满足新型无线应用对高数据速率和机动性要求的持续性增长的需求，因此他们已经开始研究被期望于2020年后就能部署的第五代无线系统。

在这篇文章里面，我们提出一个有内门和外门情景之分的潜在的蜂窝结构，并且讨论了多种可行性关于5G无线通信系统的技术，比如大量的MIMO技术，节能通信，认知的广播网络和可见光通信。

面临潜在技术的未知挑战也被讨论了。

介绍信息通信技术（ICT）创新合理的使用对世界经济的提高变得越来越重要。

无线通信网络在全球ICT战略中也许是最挑剔的元素，并且支撑着很多其他的行业，它是世界上成长最快最有活力的行业之一。

欧洲移动天文台（EMO）报道2010年移动通信业总计税收1740亿欧元,从而超过了航空航天业和制药业。

无线技术的发展大大提高了人们在商业运作和社交功能方面通信和生活的能力无线移动通信的显著成就表现在技术创新的快速步伐。

从1991年二代移动通信系统(2G)的初次登场到2001年三代系统（3G）的首次起飞，无线移动网络已经实现了从一个纯粹的技术系统到一个能承载大量多媒体内容网络的转变。

4G无线系统被设计出来用来满足IMT-A技术使用IP面向所有服务的需求。

在4G系统中，先进的无线接口被用于正交频分复用技术（OFDM），多输入多输出系统（MIMO）和链路自适应技术。

4G无线网络可支持数据速率可达1Gb/s的低流度，比如流动局域无线访问，还有速率高达100M/s的高流速，例如像移动访问。

LTE系统和它的延伸系统LTE-A，作为实用的4G系统已经在全球于最近期或不久的将来部署。

然而，每年仍然有戏剧性增长数量的用户支持移动宽频带系统。

通信工程外文文献翻译

毕业设计（论文）的外文文献翻译原始资料的题目/来源：Fundamentals of wireless communications by David Tse翻译后的中文题目：无线通信基础专业通信工程学生王晓宇学号110240318班号1102403指导教师杨洪娟翻译日期2015年6月15日外文文献的中文翻译7．mimo：空间多路复用与信道建模本书我们已经看到多天线在无线通信中的几种不同应用。

在第3章中，多天线用于提供分集增益，增益无线链路的可靠性，并同时研究了接受分解和发射分解，而且，接受天线还能提供功率增益。

在第5章中，我们看到了如果发射机已知信道，那么多采用多幅发射天线通过发射波束成形还可以提供功率增益。

在第6章中，多副发射天线用于生产信道波动，满足机会通信技术的需要，改方案可以解释为机会波束成形，同时也能够提供功率增益。

章以及接下来的几章将研究一种利用多天线的新方法。

我们将会看到在合适的信道衰落条件下，同时采用多幅发射天线和多幅接收天线可以提供用于通信的额外的空间维数并产生自由度增益，利用这些额外的自由度可以将若干数据流在空间上多路复用至MIMO信道中，从而带来容量的增加：采用n副发射天线和接受天线的这类MIMO 信道的容量正比于n。

过去一度认为在基站采用多幅天线的多址接入系统允许若干个用户同时与基站通信，多幅天线可以实现不同用户信号的空间隔离。

20世纪90年代中期，研究人员发现采用多幅发射天线和接收天线的点对点信道也会出现类似的效应，即使当发射天线相距不远时也是如此。

只要散射环境足够丰富，使得接受天线能够将来自不同发射天线的信号分离开，该结论就成立。

我们已经了解到了机会通信技术如何利用信道衰落，本章还会看到信道衰落对通信有益的另一例子。

将机会通信与MIMO技术提供的性能增益的本质进行比较和对比是非常的有远见的。

机会通信技术主要提供功率增益，改功率增益在功率受限系统的低信噪比情况下相当明显，但在宽带受限系统的高信噪比情况下则很不明显。

通信类英文文献及翻译

姓名：峻霖班级：通信143班学号：2014101108附录一、英文原文：Detecting Anomaly Trafﬁc using Flow Data in thereal VoIP networkI. INTRODUCTIONRecently, many SIP[3]/RTP[4]-based VoIP applications and services have appeared and their penetration ratio is gradually increasing due to the free or cheap call charge and the easy subscription method. Thus, some of the subscribers to the PSTN service tend to change their home telephone services to VoIP products. For example, companies in Korea such as LG Dacom, Samsung Net- works, and KT have begun to deploy SIP/RTP-based VoIP services. It is reported that more than ﬁve million users have subscribed the commercial VoIP services and 50% of all the users are joined in 2009 in Korea [1]. According to IDC, it is expected that the number of VoIP users in US will increase to 27 millions in 2009 [2]. Hence, as the VoIP service becomes popular, it is not surprising that a lot of VoIP anomaly trafﬁc has been already known [5]. So, Most commercial service such as VoIP services should provide essential security functions regarding privacy, authentication, integrity andnon-repudiation for preventing malicious trafﬁc. Particu- larly, most of current SIP/RTP-based VoIP services supply the minimal security function related with authentication. Though secure transport-layer protocols such as Transport Layer Security (TLS) [6] or Secure RTP (SRTP) [7] have been standardized, they have not been fully implemented and deployed in current VoIP applications because of the overheads of implementation and performance. Thus, un-encrypted VoIP packets could be easily sniffed and forged, especially in wireless LANs. In spite of authentication,the authentication keys such as MD5 in the SIP header could be maliciously exploited, because SIP is a text-based protocol and unencrypted SIP packets are easily decoded. Therefore, VoIP services are very vulnerable to attacks exploiting SIP and RTP. We aim at proposing a VoIP anomaly trafﬁc detection method using the ﬂow-based trafﬁc measurement archi-tecture. We consider three representative VoIP anomalies called CANCEL, BYE Denial of Service (DoS) and RTP ﬂooding attacks in this paper, because we found that malicious users in wireless LAN could easily perform these attacks in the real VoIP network. For monitoring VoIP packets, we employ the IETF IP Flow Information eXport (IPFIX) [9] standard that is based on NetFlow v9. This trafﬁc measurement method provides a ﬂexible and extensible template structure for various protocols, which is useful for observing SIP/RTP ﬂows [10]. In order to capture and export VoIP packets into IPFIX ﬂows, we deﬁne two additional IPFIX templates for SIP and RTP ﬂows. Furthermore, weadd four IPFIX ﬁelds to observe 802.11 packets which are necessary to detect VoIP source spooﬁng attacks in WLANs.II. RELATED WORK[8] proposed a ﬂooding detection method by the Hellinger Distance (HD) concept. In [8], they have pre- sented INVITE, SYN and RTP ﬂooding detection meth-ods. The HD is the difference value between a training data set and a testing data set. The training data set collected trafﬁc over n sampling period of duration Δ t.The testing data set collected trafﬁc next the training data set in the same period. If the HD is close to ‘1’, this testing data set is regarded as anomaly trafﬁc. For using this method, they assumed that initial training data set did not have any anomaly trafﬁc. Since this method was based on packet counts, it might not easily extended to detect other anomaly trafﬁc except ﬂooding. On the other hand, [11] has proposed a VoIP anomaly trafﬁc detection method using Extended Finite State Machine (EFSM). [11] has suggested INVITE ﬂooding, BYE DoS anomaly trafﬁc and media spamming detection methods. However, the state machine required more memory because it had to maintain each ﬂow. [13] has presented NetFlow-based VoIP anomaly detection methods for INVITE, REGIS-TER, RTP ﬂooding, and REGISTER/INVITE scan. How-ever, the VoIP DoS attacks considered in this paper were not considered. In [14], an IDS approach to detect SIP anomalies was developed, but only simulation results are presented. For monitoring VoIP trafﬁc, SIPFIX [10] has been proposed as an IPFIX extension. The key ideas of the SIPFIX are application-layer inspection andSDP analysis for carrying media session information. Yet, this paper presents only the possibility of applying SIPFIX to DoS anomaly trafﬁc detection and prevention. We described the preliminary idea of detecting VoIP anomaly trafﬁc in [15]. This paper elaborates BYE DoS anomaly trafﬁc and RTP ﬂooding anomaly trafﬁc detec-tion method based on IPFIX. Based on [15], we have considered SIP and RTP anomaly trafﬁc generated in wireless LAN. In this case, it is possible to generate the similiar anomaly trafﬁc with normal VoIP trafﬁc, because attackers can easily extract normal user information from unencrypted VoIP packets. In this paper, we have extended the idea with additional SIP detection methods using information of wireless LAN packets. Furthermore, we have shown the real experiment results at the commercial VoIP network.III. THE VOIP ANOMALY TRAFFIC DETECTION METHODA. CANCEL DoS Anomaly Trafﬁc DetectionAs the SIP INVITE message is not usually encrypted, attackers could extract ﬁelds necessary to reproduce the forged SIP CANCEL message by snifﬁng SIP INVITE packets, especially in wireless LANs. Thus, we cannot tell the difference between the normal SIP CANCEL message and the replicated one, because the faked CANCEL packet includes the normal ﬁelds inferred from the SIP INVITE message. The attacker will perform the SIP CANCEL DoS attack at the same wireless LAN, because the purpose of the SIP CANCEL attack is to prevent the normal call estab-lishment when a victim is waiting for calls. Therefore, as soonas the attacker catches a call invitation message for a victim, it will send a SIP CANCEL message, which makes the call establishment failed. We have generated faked SIP CANCEL message using sniffed a SIP INVITE message.Fields in SIP header of this CANCEL message is the same as normal SIP CANCEL message, because the attacker can obtain the SIP header ﬁeld from unencrypted normal SIP message in wireless LAN environment. Therefore it is impossible to detect the CANCEL DoS anomaly trafﬁc using SIP headers, we use the different values of the wireless LAN frame. That is, the sequence number in the 802.11 frame will tell the difference between a victim host and an attacker. We look into source MAC address and sequence number in the 802.11 MAC frame including a SIP CANCEL message as shown in Algorithm 1. We compare the source MAC address of SIP CANCEL packets with that of the previously saved SIP INVITE ﬂow. If the source MAC address of a SIP CANCEL ﬂow is changed, it will be highly probable that the CANCEL packet is generated by a unknown user. However, the source MAC address could be spoofed. Regarding 802.11 source spooﬁng detection, we employ the method in [12] that uses sequence numbers of 802.11 frames. We calculate the gap between n-th and (n-1)-th 802.11 frames. As the sequence number ﬁeld in a 802.11 MAC header uses 12 bits, it varies from 0 to 4095. When we ﬁnd that the sequence number gap between a single SIP ﬂow is greater than the threshold value of N that will be set from the experiments, we determine that the SIP host address as been spoofed for the anomaly trafﬁc.B. BYE DoS Anomaly Trafﬁc DetectionIn commercial VoIP applications, SIP BYE messages use the same authentication ﬁeld is included in the SIP IN-VITE message for security and accounting purposes. How-ever, attackers can reproduce BYE DoS packets through snifﬁng normal SIP INVITE packets in wireless LANs.The faked SIP BYE message is same with the normal SIP BYE. Therefore, it is difﬁcult to detect the BYE DoS anomaly trafﬁc using only SIP header information.After snifﬁng SIP INVITE message, the attacker at the same or different subnets could terminate the normal in- progress call, because it could succeed in generating a BYE message to the SIP proxy server. In the SIP BYE attack, it is difﬁcult to distinguish from the normal call termination procedure. That is, we apply the timestamp of RTP trafﬁc for detecting the SIP BYE attack. Generally, after normal call termination, the bi-directional RTP ﬂow is terminated in a bref space of time. However, if the call termination procedure is anomaly, we can observe that a directional RTP media ﬂow is still ongoing, whereas an attacked directional RTP ﬂow is broken. Therefore, in order to detect the SIP BYE attack, we decide that we watch a directional RTP ﬂow for a long time threshold of N sec after SIP BYE message. The threshold of N is also set from the experiments.Algorithm 2 explains the procedure to detect BYE DoS anomal trafﬁc using captured timestamp of the RTP packet. We maintain SIP session information between clients with INVITE and OK messages including the same Call-ID and 4-tuple (source/destination IP Address and port number) of the BYEpacket. We set a time threshold value by adding Nsec to the timestamp value of the BYE message. The reason why we use the captured timestamp is that a few RTP packets are observed under 0.5 second. If RTP trafﬁc is observed after the time threshold, this will be considered as a BYE DoS attack, because the VoIP session will be terminated with normal BYE messages. C. RTP Anomaly Trafﬁc Detection Algorithm 3 describes an RTP ﬂooding detection method that uses SSRC and sequence numbers of the RTP header. During a single RTP session, typically, the same SSRC value is maintained. If SSRC is changed, it is highly probable that anomaly has occurred. In addition, if there is a big sequence number gap between RTP packets, we determine that anomaly RTP trafﬁc has happened. As inspecting every sequence number for a packet is difﬁcult, we calculate the sequence number gap using the ﬁrst, last, maximum and minimum sequence numbers. In the RTP header, the sequence number ﬁeld uses 16 bits from 0 to 65535. When we observe a wide sequence number gap in our algorithm, we consider it as an RTP ﬂooding attack.IV. PERFORMANCE EVALUATIONA. Experiment EnvironmentIn order to detect VoIP anomaly trafﬁc, we established an experimental environment as ﬁgure 1. In this envi-ronment, we employed two VoIP phones with wireless LANs, one attacker, a wireless access router and an IPFIX ﬂow collector. For the realistic performance evaluation, we directly used one of the working VoIP networks deployed in Korea where an 11-digit telephone number (070-XXXX-XXXX) has been assigned to a SIP phone.With wireless SIP phones supporting 802.11, we could make calls to/from the PSTN or cellular phones. In the wireless access router, we used two wireless LAN cards- one is to support the AP service, and the other is to monitor 802.11 packets. Moreover, in order to observe VoIP packets in the wireless access router, we modiﬁed nProbe [16], that is an open IPFIX ﬂow generator, to create and export IPFIX ﬂows related with SIP, RTP, and 802.11 information. As the IPFIX collector, we have modiﬁed libipﬁx so that it could provide the IPFIX ﬂow decoding function for SIP, RTP, and 802.11 templates. We used MySQL for the ﬂow DB.B. Experimental ResultsIn order to evaluate our proposed algorithms, we gen-erated 1,946 VoIP calls with two commercial SIP phones and a VoIP anomaly trafﬁc generator. Table I shows our experimental results with precision, recall, and F-score that is the harmonic mean of precision and recall. In CANCEL DoS anomaly trafﬁc detection, our algorithm represented a few false negative cases, which was related with the gap threshold of the sequence number in 802.11 MAC header. The average of the F-score value for detecting the SIP CANCEL anomaly is 97.69%.For BYE anomaly tests, we generated 755 BYE mes-sages including 118 BYE DoS anomalies in the exper-iment. The proposed BYE DoS anomaly trafﬁc detec-tion algorithm found 112 anomalies with the F-score of 96.13%. If an RTP ﬂow is terminated before the threshold, we regard the anomaly ﬂow as a normal one. In this algorithm, we extract RTP session information from INVITE and OK or session description messages using the same Call-ID of BYE message. It is possible not to capture those packet, resulting in a few false-negative cases. The RTP ﬂooding anomaly trafﬁc detection experiment for 810 RTP sessions resulted in the F score of 98%.The reason of false-positive cases was related with the sequence number in RTP header. If the sequence number of anomaly trafﬁc is overlapped with the range of the normal trafﬁc, our algorithm will consider it as normal trafﬁc.V. CONCLUSIONSWe have proposed a ﬂow-based anomaly trafﬁc detec-tion method against SIP and RTP-based anomaly trafﬁc in this paper. We presented VoIP anomaly trafﬁc detection methods with ﬂow data on the wireless access router. We used the IETF IPFIX standard to monitor SIP/RTP ﬂows passing through wireless access routers, because its template architecture is easily extensible to several protocols. For this purpose, we deﬁned two new IPFIX templates for SIP and RTP trafﬁc and four new IPFIX ﬁelds for 802.11 trafﬁc. Using these IPFIX ﬂow templates,we proposed CANCEL/BYE DoS and RTP ﬂooding trafﬁc detection algorithms. From experimental results on the working VoIP network in Korea, we showed that our method is able to detect three representative VoIP attacks on SIP phones. In CANCEL/BYE DoS anomaly trafﬁcdetection method, we employed threshold values about time and sequence number gap for classﬁcation of normal and abnormal VoIP packets. This paper has not been mentioned the test result about suitable threshold values. For the future work, we will show the experimental result about evaluation of the threshold values for our detection method.二、英文翻译：交通流数据检测异常在真实的世界中使用的VoIP网络一 .介绍最近,多SIP[3],[4]基于服务器的VoIP应用和服务出现了,并逐渐增加他们的穿透比及由于自由和廉价的通话费且极易订阅的法。

计算机第五代5g移动通讯通信技术介绍简介概述外文文献翻译成品：5G的五个颠覆性技术方向中英文双语对照

Five Disruptive Technology Directions for 5G ABSTRACT: New research directions will lead to fundamental changes in the design of future 5th generation (5G) cellular networks. This paper describes five technologies that could lead to both architectural and component disruptive design changes: device-centric architectures, millimeter Wave, Massive-MIMO, smarter devices, and native support to machine-2-machine. The key ideas for each technology are described, along with their potential impact on 5G and the research challenges that remain.I.INTRODUCTION:5G is coming. What technologies will define it? Will 5G be just an evolution of 4G, or will emerging technologies cause a disruption requiring a wholesale rethinking of entrenched cellular principles? This paper focuses on potential disruptive technologies and their implications for 5G. We classify the impact of new technologies, leveraging the Henderson-Clark model [1], as follows:1.Minor changes at both the node and the architectural level, e.g., the introduction of codebooks and signaling support for a higher number of antennas. We refer to these as evolutions in the design.2.Disruptive changes in the design of a class of network nodes, e.g., the introduction of a new waveform. We refer to these as component changes.3.Disruptive changes in the system architecture, e.g., the introduction of new types of nodes or new functions in existing ones. We refer to these as architectural changes.4.Disruptive changes that have an impact at both the node and the architecture levels. We refer to these as radical changes.We focus on disruptive (component, architectural or radical) technologies, driven by our belief that the extremely higher aggregate data rates and the much lower latencies required by 5G cannot be achieved with a mere evolution of the status quo. We believe that the following five potentially disruptive technologies could lead to both architectural and component design changes, as classified in Figure 1.1.Device-centric architectures.The base-station-centric architecture of cellular systems may change in 5G. It may be time to reconsider the concepts of uplink and downlink, as well as control and data channels, to better route information flows with different priorities and purposes towards different sets of nodes within the network. We present device-centric architectures in Section II.limeter Wave (mmWave).While spectrum has become scarce at microwave frequencies, it is plentiful in the mmWave realm. Such a spectrum ‘el Dorado’ has led to a mmWave ‘gold rush’ in which researchers with diverse backgrounds are studying different aspects ofmmWave transmission. Although far from fully understood, mmWave technologies have already been standardized for short-range services (IEEE 802.11ad) and deployed for niche applications such as small-cell backhaul. In Section III, we discuss the potential of mmWave for a broader application in 5G.3.Massive-MIMO.Massive-MIMO1 proposes utilizing a very high number of antennas to multiplex messages for several devices on each time-frequency resource, focusing the radiated energy towards the intended directions while minimizing intra-and inter-cell interference. Massive-MIMO may require major architectural changes, in particular in the design of macro base stations, and it may also lead to new types of deployments. We discuss massive-MIMO in Section IV.4.Smarter devices.2G-3G-4G cellular networks were built under the design premise of having complete control at the infrastructure side. We argue that 5G systems should drop this design assumption and exploit intelligence at the device side within different layers of the protocol stack, e.g., by allowing Device-to-Device (D2D) connectivity or by exploiting smart caching at the mobile side. While this design philosophy mainly requires a change at the node level (component change), it has also implications at the architectural level. We argue for smarter devices in Section V.5.Native support for Machine-to-Machine (M2M) communicationA native2 inclusion of M2M communication in 5G involves satisfying three fundamentally different requirements associated to different classes of low-data-rate services: support of a massive number of low-rate devices, sustainment of a minimal data rate in virtually all circumstances, and very-low-latency data transfer. Addressing these requirements in 5G requires new methods and ideas at both the component and architectural level, and such is the focus of Section VI.II.DEVICE-CENTRIC ARCHITECTURESCellular designs have historically relied on the axiomatic role of ‘cells’ as fundamental units within the radio access network. Under such a design postulate, a device obtains service by establishing a downlink and an uplink connection, carrying both control and data traffic, with the base station commanding the cell where the device is located. Over the last few years, different trends have been pointing to a disruption of this cell-centric structure:1.The base-station density is increasing rapidly, driven by the rise of heterogeneous networks. While heterogeneous networks were already standardized in 4G, the architecture was not natively designed to support them. Network densification could require some major changes in 5G. The deployment of base stations with vastly different transmit powers and coverage areas, for instance, calls for a decoupling of downlink and uplink in a way that allows for the corresponding information to flow through different sets of nodes [5].2.The need for additional spectrum will inevitably lead to the coexistence of frequency bands with radically different propagation characteristics within the same system. In this context, [6] proposes the concept of a ‘phantom cell’ where the data and control planes are separated: the control information is sent by high-power nodes at microwave frequencies whereas the payload data is conveyed by low-power nodes at mm-Wave frequencies. (cf. Section III.)3.A new concept termed centralized baseband related to the concept of cloud radioaccess networks is emerging (cf. [7]), where virtualization leads to a decoupling between a node and the hardware allocated to handle the processing associated with this node. Hardware resources in a pool, for instance, could be dynamically allocated to different nodes depending on metrics defined by the network operator.Emerging service classes, described in Section VI, could require a complete redefinition of the architecture. Current works are looking at architectural designs ranging from centralization or partial centralization (e.g., via aggregators) to full distribution (e.g., via compressed sensing and/or multihop).Cooperative communications paradigms such as CoMP or relaying, which despite falling short of their initial hype are nonetheless beneficial [8], could require a redefinition of the functions of the different nodes. In the context of relaying, for instance, recent developments in wireless network coding [9] suggest transmission principles that would allow recovering some of the losses associated with half-duplex relays. Moreover, recent research points to the plausibility of full- duplex nodes for short-range communication in a not-so-distant future.The use of smarter devices (cf. Section V) could impact the radio access network. In particular, both D2D and smart caching call for an architectural redefinition where the center of gravity moves from the network core to the periphery (devices, local wireless proxies, relays). Based on these trends, our vision is that the cell-centric architecture should evolve into a device-centric one: a given device (human or machine) should be able to communicate by exchanging multiple information flows through several possible sets of heterogeneous nodes. In other words, the set of network nodes providing connectivity to a given device and the functions of these nodes in a particular communication session should be tailored to that specific device and session. Under this vision, the concepts of uplink/downlink and control/data channel should be rethought (cf. Figure 2).While the need for a disruptive change in architectural design appears clear, major research efforts are still needed to transform the resulting vision into a coherent and realistic proposition. Since the history of innovations (cf. [1]) indicates that architectural changes are often the drivers of major technological discontinuities, we believe that the trends above might have a major influence on the development of 5G.LIMETER WA VE COMMUNICATIONMicrowave cellular systems have precious little spectrum: around 600 MHz are currently in use, divided among operators [10]. There are two ways to gain access to more microwave spectrum:1.To repurpose or refarm spectrum. This has occurred worldwide with the repurposing of terrestrial TV spectrum for applications such as rural broadband access. Unfortunately, repurposing has not freed up that much spectrum, only about 80 MHz, and at a high cost associated with moving the incumbents.2.To share spectrum utilizing, for instance, cognitive radio techniques. The high hopes initially placed on cognitive radio have been dampened by the fact that an incumbent not fully willing to cooperate is a major obstacle to spectrum efficiency for secondary users.3.Altogether, it appears that a doubling of the current cellular bandwidth is the best-case scenario at microwave frequencies. Alternatively, there is an enormous amount of spectrum at mmWave frequencies ranging from 3 to 300 GHz. Many bands therein seem promising, including most immediately the local multipoint distribution service at 28-30 GHz, the license-free band at 60 GHz, and the E-band at 71-76 GHz, 81-86 GHz and 92-95 GHz. Foreseeably, several tens of GHz could become available for 5G, offering well over an order-of-magnitude increase over what is available atpresent. Needless to say, work needs to be done on spectrum policy to render these bands available for mobile cellular.3.Propagation is not an insurmountable challenge. Recent measurements indicate similar general characteristics as at microwave frequencies, including distance-dependent pathloss and the possibility of non-line-of-sight communication. A main difference between microwave and mmWave frequencies is the sensitivity to blockages: the results in [11], for instance, indicate a pathloss exponent of 2 for line-of-sight propagation but 4 (plus an additional power loss) for non-line-of-sight. MmWave cellular research will need to incorporate sensitivity to blockages and more complex channel models into the analysis, and also study the effects of enablers such as higher density infrastructure and relays. Another enabler is the separation between control and data planes, already mentioned in Section II.Antenna arrays are a key feature in mmWave systems. Large arrays can be used to keep the antenna aperture constant, eliminating the frequency dependence of pathloss relative to omnidirectional antennas (when utilized at one side of the link) and providing a net array gain to counter the larger thermal noise bandwidth (when utilized at both sides of the link). Adaptive arrays with narrow beams also reduce the impact of interference, meaning that mmWave systems could more often operate in noise-limited rather than interference-limited conditions. Since meaningful communication might only happen under sufficient array gain, new random access protocols are needed that work when transmitters can only emit in certain directions and receivers can only receive from certain directions. Adaptive array processing algorithms are required that can adapt quickly when beams are blocked by people or when some device antennas become obscured by the user’s own body.MmWave systems also have distinct hardware constraints. A major one comes from the high power consumption of mixed signal components, chiefly the analog-to-digital (ADC) and digital-to-analog converters (DAC). Thus, the conventional microwave architecture where every antenna is connected to a high-rate ADC/DAC is unlikely to be applicable to mmWave without a huge leap forward in semiconductor technology. One alternative is a hybrid architecture where beamforming is performed in analog at RF and multiple sets of beamformers are connected to a small number of ADCs or DACS; in this alternative, signal processing algorithms are needed to steer the analog beamforming weights. Another alternative is to connect each RF chain to a 1-bit ADC/DAC, with very low power requirements; in this case, the beamforming would be performed digitally but on very noisy data. There are abundant research challenges in optimizing different transceiver strategies, analyzing their capacity, incorporating multiuser capabilities, and leveraging channel features such as sparsity.A data rate comparison between technologies is provided in Fig. 3, for certain simulation settings, in terms of mean and 5% outage rates. MmWave operation is seento provide very high rates compared to two different microwave systems. The gains exceed the 10x spectrum increase because of the enhanced signal power and reduced interference thanks to directional beamforming at both transmitter and receiver.IV.MASSIVE MIMOMassive MIMO (also referred to as ‘Large-Scale MIMO’ or ‘Large-Scale Antenna Systems’) is a form of multiuser MIMO in which the number of antennas at the base station is much larger than the number of devices per signaling resource [14]. Having many more base station antennas than devices renders the channels to the different devices quasi-orthogonal and very simple spatial multiplexing/de-multiplexing procedures quasi-optimal. The favorable action of the law of large numbers smoothens out frequency dependencies in the channel and, altogether, huge gains in spectral efficiency can be attained (cf. Fig. 4).In the context of the Henderson-Clark framework, we argue that massive-MIMO has a disruptive potential for 5G:At a node level, it is a scalable technology. This is in contrast with 4G, which, in many respects, is not scalable: further sectorization therein is not feasible because of (i) the limited space for bulky azimuthally-directive antennas, and (ii) the inevitable angle spread of the propagation; in turn, single-user MIMO is constrained by the limited number of antennas that can fit in certain mobile devices. In contrast, there is almost no limit on the number of base station antennas in massive- MIMO provided that time-division duplexing is employed to enable channel estimation through uplink pilots.It enables new deployments and architectures. While one can envision direct replacement of macro base stations with arrays of low-gain resonant antennas, other deployments are possible, e.g., conformal arrays on the facades of skyscrapers or arrays on the faces of water tanks in rural locations. Moreover, the same massive-MIMO principles that govern the use of collocated arrays of antennas applyalso to distributed deployments in which a college campus or an entire city could be covered with a multitude of distributed antennas that collectively serve many users (in this framework, the centralized baseband concept presented in Section II is an important architectural enabler).While very promising, massive-MIMO still presents a number of research challenges. Channel estimation is critical and currently it represents the main source of limitations. User motion imposes a finite coherence interval during which channel knowledge must be acquired and utilized, and consequently there is a finite number of orthogonal pilot sequences that can be assigned to the devices. Reuse of pilot sequences causes pilot contamination and coherent interference, which grows with the number of antennas as fast as the desired signals. The mitigation of pilot contamination is an active research topic. Also, there is still much to be learned about massive-MIMO propagation, although experiments thus far support the hypothesis of channel quasi-orthogonality. From an implementation perspective, massive-MIMO can potentially be realized with modular low-cost low-power hardware with each antenna functioning semi-autonomously, but a considerable development effort is still required to demonstrate the cost-effectiveness of this solution. Note that, at the microwave frequencies considered in this section, the cost and the energy consumption of ADCs/DACs are sensibly lower than at mmWave frequencies (cf. Section III).From the discussion above, we conclude that the adoption of massive-MIMO for 5G could represent a major leap with respect to today’s state-of-the-art in system and component design. To justify these major changes, massive-MIMO proponents should further work on solving the challenges emphasized above and on showing realistic performance improvements by means of theoretical studies, simulation campaigns, and testbed experiments.V.SMARTER DEVICESEarlier generations of cellular systems were built on the design premise of having complete control at the infrastructure side. In this section, we discuss some of the possibilities that can be unleashed by allowing the devices to play a more active role and, thereafter, how 5G’s design should account for an increase in device smartness. We focus on three different examples of technologies that could be incorporated into smarter devices, namely D2D, local caching, and advanced interference rejection.V.1 D2DIn voice-centric systems it was implicitly accepted that two parties willing to establish a call would not be in close proximity. In the age of data, this premise might no longer hold, and it could be common to have situations where several co-located devices would like to wirelessly share content (e.g., digital pictures) or interact (e.g., video gaming or social networking). Handling these communication scenarios via simply connecting through the network involves gross inefficiencies at various levels:1.Multiple wireless hops are utilized to achieve what requires, fundamentally, a single hop. This entails a multifold waste of signaling resources, and also a higher latency. Transmit powers of a fraction of a Watt (in the uplink) and several Watts (in the downlink) are consumed to achieve what requires, fundamentally, a few milliWatts. This, in turn, entails unnecessary levels of battery drain and of interference to all other devices occupying the same signaling resources elsewhere.2.Given that the pathlosses to possibly distant base stations are much stronger than the direct-link ones, the corresponding spectral efficiencies are also lower. While it is clear that D2D has the potential of handling local communication more efficiently, local high-data-rate exchanges could also be handled by other radio access technologies such as Bluetooth or Wi-Fi direct. Use cases requiring a mixture of local and nonlocal content or a mixture of low-latency and high- data-rate constraints (e.g., interaction between users via augmented reality), could represent more compelling reasons for the use of D2D. In particular, we envision D2D as an important enabler for applications requiring low-latency 3 , especially in future network deployments utilizing baseband centralization and radio virtualization (cf. Section I).From a research perspective, D2D communication presents relevant challenges:1.Quantification of the real opportunities for D2D. How often does local communication occur? What is the main use case for D2D: fast local exchanges, low-latency applications or energy saving?2.Integration of a D2D mode with the uplink/downlink duplexing structure.3.Design of D2D-enabled devices, from both a hardware and a protocol perspective, by providing the needed flexibility at both the PHY and MAC layers.4.Assessing the true net gains associated with having a D2D mode, accounting for possible extra overheads for control and channel estimation.5.Finally, note that, while D2D is already being studied in 3GPP as a 4G add-on2, the main focus of current studies is proximity detection for public safety [15]. What wediscussed here is having a D2D dimension natively supported in 5G.V.2 Local CachingThe current paradigm of cloud computing is the result of a progressive shift in the balance between data storage and data transfer: information is stored and processed wherever it is most convenient and inexpensive because the marginal cost of transferring it has become negligible, at least on wireline networks [2]. For wireless devices though, this cost is not always negligible. The understanding that mobile users are subject to sporadic ‘abundance’ of connectivity amidst stretches of ‘deprivation’ is hardly new, and the natural idea of opportunistically leveraging the former to alleviate the latter has been entertained since the 1990s [3]. However, this idea of caching massive amounts of data at the edge of the wireline network, right before the wireless hop, only applies to delay-tolerant traffic and thus it made little sense in voice-centric systems. Caching might finally make sense now, in data-centric systems [4]. Thinking ahead, it is easy to envision mobile devices with truly vast amounts of memory. Under this assumption, and given that a substantial share of the data that circulates wirelessly corresponds to the most popular audio/video/social content that is in vogue at a given time, it is clearly inefficient to transmit such content via unicast and yet it is frustratingly impossible to resort to multicast because the demand is asynchronous. We hence see local caching as an important alternative, both at the radio access network edge (e.g., at small cells) and at the mobile devices, also thanks to enablers such as mmWave and D2D.V.3 Advanced Interference RejectionIn addition to D2D capabilities and massive volumes of memory, future mobile devices may also have varying form factors. In some instances, the devices mightaccommodate several antennas with the consequent opportunity for active interference rejection therein, along with beamforming and spatial multiplexing. A joint design of transmitter and receiver processing, and proper control and pilot signals, are critical to allow advanced interference rejection. As an example, in Fig. 5 we show the gains obtained by incorporating the effects of nonlinear, intra and inter-cluster interference awareness into devices with 1, 2 and 4 antennas.While this section has been mainly focused on analyzing the implications of smarter devices at a component level, in Section II we discussed the impact at the radio access network architecture level. We regard smarter devices as having all the characteristic of a disruptive technology (cf. Section I) for 5G, and therefore we encourage researchers to further explore this direction.VI.NATIVE SUPPORT FOR M2M COMMUNICATIONWireless communication is becoming a commodity, just like electricity or water [13]. This commoditization, in turn, is giving rise to a large class of emerging services with new types of requirements. We point to a few representative such requirements, each exemplified by a typical service:1.A massive number of connected devices. Whereas current systems typically operate with, at most, a few hundred devices per base station, some M2M services might require over 104 connected devices. Examples include metering, sensors, smart grid components, and other enablers of services targeting wide area coverage.2.Very high link reliability. Systems geared at critical control, safety, or production, have been dominated by wireline connectivity largely because wireless links did not offer the same degree of confidence. As these systems transition from wireline to wireless, it becomes necessary for the wireless link to be reliably operational virtually all the time.3.Low latency and real-time operation. This can be an even more stringent requirement than the ones above, as it demands that data be transferred reliably within a given time interval. A typical example is Vehicle-to-X connectivity, whereby traffic safety can be improved through the timely delivery of critical messages (e.g., alert and control).Fig. 5 provides a perspective on the M2M requirements by plotting the data rate vs. the device population size. This cartoon illustrates where systems currently stand and how the research efforts are expanding them. The area R1 reflects the operating range of today’s systems, outlining the fact that the device data rate decreases as its population increases. In turn, R2 is the region that reflects current research aimed at improving the spectral efficiency. Finally, R5 indicates the region where operation is not feasible due to fundamental physical and information-theoretical limits.Regions R3 and R4 correspond to the emerging services discussed in this section:R3 refers to massive M2M communication where each connected machine or sensor transmits small data blocks sporadically. Current systems are not designed to simultaneously serve the aggregated traffic accrued from a large number of such devices. For instance, a current system could easily serve 5 devices at 2 Mbps each, but not 10000 devices each requiring 1 Kbps. R4 demarks the operation of systems that require high reliability and/or low latency, but with a relatively low average rate per device. The complete description of this region requires additional dimensions related to reliability and latency.There are services that pose simultaneously more than one of the above requirements, but the common point is that the data size of each individual transmission is small, going down to several bytes. This profoundly changes the communication paradigm for the following reasons:Existing coding methods that rely on long codewords are not applicable to very short data blocks. Short data blocks also exacerbate the inefficiencies associated with control and channel estimation overheads. Currently, the control plane is robust but suboptimal as it represents only a modest fraction of the payload data; the most sophisticated signal processing is reserved for payload data transmission. An optimized design should aim at a much tighter coupling between the data and control planes.As mentioned in Section II, the architecture needs a major redesign, looking at new types of nodes. At a system level, the frame-based approaches that are at the heart of 4G need rethinking in order to meet the requirements for latency and flexible allocation of resources to a massive number of devices. From the discussion above, and from the related architectural consideration in Section II, and referring one last time to the Henderson-Clark model, we conclude that a native support of M2M in 5G requires radical changes at both the node and the architecture level. Major research work remains to be done to come up with concrete and interworking solutionsenabling ‘M2M-inside’ 5G systems.VII.CONCLUSIONThis paper has discussed five disruptive research directions that could lead to fundamental changes in the design of cellular networks. We have focused on technologies that could lead to both architectural and component design changes: device-centric architectures, mmWave, massive-MIMO, smarter devices, and native support to M2M. It is likely that a suite of these solutions will form the basis of 5G. REFERENCES[1] A. Afuah, Innovation Management: Strategies, Implementation and Profits, Oxford University Press, 2003.[2] J. Zander and P. Mähönen, “Riding the data tsunami in the cloud: myths and challenges in future wireless access,” IEEE Comm. Magazine, V ol. 51, No. 3, pp. 145-151, Mar. 2013.[3] D. Goodman, J. Borras, N. Mandayam, R. D. Yates, “Infostations: A new system model for data and messaging services,” in Proc. IEEE Veh. Techn. Conf. (VTC), vol. 2, pp. 969–973, Rome, Italy, May 1997.[4] N. Golrezaei, A. F. Molisch, A. G. Dimakis and G. Caire, “Femtocaching and device-to-device collaboration: A new architecture for wireless video distribution,” IEEE Comm. Magazine, V ol. 51, No. 1, pp.142-149, Apr. 2013.[5] J. Andrews, “The seven ways HetNets are a paradigm shift,” IEEE Comm. Magazine, V ol. 51, No. 3, pp.136-144, Mar. 2013.[6] Y. Kishiyama, A. Benjebbour, T. Nakamura and H. Ishii, “Future steps of LTE-A: evolution towards integration of local area and wide area systems,” IEEE Wireless Communications, V ol. 20, No. 1, pp.12-18, Feb. 2013.[7] “C-RAN: The road towards green RAN,” China Mobile Res. Inst., Beijing, China, White Paper, ver. 2.5, Oct. 2011.[8] A. Lozano, R. W. Heath Jr., J. G. Andrews, “Fundamental limits of cooperation,” IEEE Trans. Inform. Theory, V ol. 59, No. 9, pp. 5213-5226, Sep. 2013.[9] C. D. T. Thai, P. Popovski, M. Kaneko, and E. de Carvalho, “Multi-flow scheduling for coordinated direct and relayed users in cellular systems,” IEEE Trans. Comm., V ol. 61, No. 2, pp. 669-678, Feb. 2013.[10] Z. Pi and F. Khan, “An introduction to millimeter-wave mobile broadband systems,” IEEE Comm. Magazine, V ol. 49, No. 6, pp. 101 –107, Jun. 2011.[11] T. Rappaport and et al, “Millimeter wave mobile communications for 5G cellular: It will work!” IEEE Access, vol. 1, pp. 335–349, 2013.[12] R. W. Heath Jr., “What is the Role of MIMO in Future Cellular Networks: Massive? Coordinated? mmWave?” ICC Workshop Plenary: Beyond LTE-A, Budapest, Hungary. Slides available at: /~rheath/presentations/2013/Future_of_MIMO_Plenary_He ath.pdf[13] Mark Weiser, “The Computer for the 21st Century,” Scientific American, Sept. 1991.。

通信工程移动通信中英文对照外文翻译文献

中英文翻译(文档含英文原文和中文翻译)附件1：外文资料翻译译文通用移动通信系统的回顾1.1 UMTS网络架构欧洲/日本的3G标准，被称为UMTS。

UMTS是一个在IMT-2000保护伞下的ITU-T 批准的许多标准之一。

随着美国的CDMA2000标准的发展，它是目前占主导地位的标准，特别是运营商将cdmaOne部署为他们的2G技术。

在写这本书时，日本是在3G 网络部署方面最先进的。

三名现任运营商已经实施了三个不同的技术：J - PHONE 使用UMTS，KDDI拥有CDMA2000网络，最大的运营商NTT DoCoMo正在使用品牌的FOMA（自由多媒体接入）系统。

FOMA是基于原来的UMTS协议，而且更加的协调和标准化。

UMTS标准被定义为一个通过通用分组无线系统（GPRS）和全球演进的增强数据技术（EDGE）从第二代GSM标准到UNTS的迁移，如图。

这是一个广泛应用的基本原理，因为自2003年4月起，全球有超过847万GSM用户，占全球的移动用户数字的68％。

重点是在保持尽可能多的GSM网络与新系统的操作。

我们现在在第三代（3G）的发展道路上，其中网络将支持所有类型的流量：语音，视频和数据，我们应该看到一个最终的爆炸在移动设备上的可用服务。

此驱动技术是IP协议。

现在，许多移动运营商在简称为2.5G的位置，伴随GPRS的部署，即将IP骨干网引入到移动核心网。

在下图中，图2显示了一个在GPRS网络中的关键部件的概述，以及它是如何适应现有的GSM基础设施。

SGSN和GGSN之间的接口被称为Gn接口和使用GPRS隧道协议（GTP的，稍后讨论）。

引进这种基础设施的首要原因是提供连接到外部分组网络如，Internet或企业Intranet。

这使IP协议作为SGSN和GGSN之间的运输工具应用到网络。

这使得数据服务，如移动设备上的电子邮件或浏览网页，用户被起诉基于数据流量，而不是时间连接基础上的数据量。

通信工程外文翻译文献

中英文对照外文翻译文献(文档含英文原文和中文翻译)计算机网络冗余GPS时间同步电路板的设计与实现摘要：如今，在计算机网络系统中准确和可靠的时间是一个基本要求。

为实现这一必要性，时间同步想法产生了。

同时在某些情况下，可靠的时间是如此的重要，以致于一个冗余的结构得以应用。

在本文中，时间同步系统的主要研究是设计和实施一个时间同步电路，该电路能够通过NTP协议与计算机网络同步时间。

在本设计中还嵌入了冗余方案以便提供更高的可靠性。

关键字：计算机网络GPS时间NTP 冗余时间同步时间同步协议时间服务器1. 引言我们通常会把电脑的时间和手表的误差设置在一两分钟内，但另一方面，准确和可靠的时间对于财务和法律事务、运输、分销系统，和许多其他涉及资源分布广泛的应用程序是必要的。

举一个例子说明，在一个分布式的机票预订系统，如果分布式计算机时间不同，座椅可以卖出两倍价格甚至更多，或者在网上股票交易完成之前会产生法律后果。

在这方面，世界协调时和时钟同步已开发出来。

基础的时间尺度已随着历史得到改进，以地球自转为基础的地球时和原子时也产生了。

一些重要的时间尺度还包括国际原子时（TAI）、通用协调时间尺度（UTC）、和标准时间或民用时间。

时钟同步协议的想法是，即使最初设置准确，但电脑的内部时钟也可能与世界时钟不同。

之后，由于时钟漂移，会有相当大的误差，所以总是有必要将这些漂移的时钟同步到参考时钟源。

时间同步源包括地球上的无线电同步技术（WWV, WWVH, WWVB, DCF77 and LORAN-C）、卫星时间同步技术（GOES, GPS, GLONASS, and Galileo）、互联网时间同步技术以及电话拨号时间同步技术。

在这些时钟源中，全球定位系统（GPS）提供了一些特殊的优点，如时间精度、抗噪声干扰、在世界各地都可用、并不断引用国际标准。

如今，相比其他时钟资源，全球定位系统时钟的使用更为广泛。

图1显示了一个典型的时间同步结构，其中时间服务器从GPS接收的数据作为时间同步源。

5G无线通信网络中英文对照外文翻译文献

然而，随着无线移动设备和服务的激增，仍然有一些挑战尤其是4G所不能容纳的，例如像频谱危机和高能量消耗。

面临潜在技术的未知挑战也被讨论了。

介绍信息通信技术（ICT）创新合理的使用对世界经济的提高变得越来越重要。

无线通信网络在全球ICT战略中也许是最挑剔的元素，并且支撑着很多其他的行业，它是世界上成长最快最有活力的行业之一。

欧洲移动天文台（EMO）报道2010年移动通信业总计税收1740亿欧元,从而超过了航空航天业和制药业。

无线技术的发展大大提高了人们在商业运作和社交功能方面通信和生活的能力无线移动通信的显著成就表现在技术创新的快速步伐。

4G无线系统被设计出来用来满足IMT-A技术使用IP面向所有服务的需求。

在4G系统中，先进的无线接口被用于正交频分复用技术（OFDM），多输入多输出系统（MIMO）和链路自适应技术。

4G无线网络可支持数据速率可达1Gb/s的低流度，比如流动局域无线访问，还有速率高达100M/s的高流速，例如像移动访问。

LTE系统和它的延伸系统LTE-A，作为实用的4G系统已经在全球于最近期或不久的将来部署。

然而，每年仍然有戏剧性增长数量的用户支持移动宽频带系统。

通信工程光纤滤波器中英文对照外文翻译文献

中英文翻译(文档含英文原文和中文翻译)译文一：基于一个高双折射光纤双Sagnac环的可调谐多波长光纤激光器1．引言工作在波长1550nm附近的多波长光纤激光器已经吸引了许多人的兴趣，它可以应用于密集波分复用（DWDM）系统，精细光谱学，光纤传感和微波（RF）光电[1-4]等领域。

多波长光纤激光器可以通过布拉格光纤光栅阵列[5]，锁模技术[6-7]，光学参量振荡器[8]，四波混频效应[9]，受激布里渊散射效应实现[10-12]。

掺铒光纤（EDF）环形激光器可以提供大输出功率，高斜度效率和大可调谐波长范围。

例如，作为一种可调谐EDF激光器，带有单个高双折射光纤Sagnac 环的多波长光纤激光器已经提出[13-15]。

输出波长可以通过调整偏振控制器（PC）进行调谐，波长间隔可以通过改变保偏光纤（PMF）的长度进行调谐。

然而，对于单个Sagnac环光纤激光器来说，波长间隔和线宽都不能独立调谐[16]。

密集波分复用（DWDM）系统要求激光波长调谐更灵活，否则会限制这些激光器的应用。

一个双Sagnac环的多波长光纤激光器能提供更好的可调谐性和可控性。

采用这种结构，可以实现保持线宽不变的波长间隔可调谐，以及保持波长间隔不变的线宽调谐。

本文提出和证明了一种双Sagnac环可调谐多波长掺铒光纤环形激光器。

多波长选择由两个Sagnac 环实现，而每个环由一个3dB 耦合器，一个PC ，和一段高双折射PMF 组成。

本文模拟分析了单个和两个Sagnac 环的梳状滤波器的特征。

实验中，得到输出激光的半峰全宽（FWHM ）是0.0187nm ，边模抑制比（SMSR ）是50dB 。

通过调整两个PC 可以实现多波长激光器输出的大范围调谐。

与单环结构相比，改变PMF 长度可以独立调谐波长间隔和激光线宽。

本文中提出的双Sagnac 环光纤激光器是先前单Sagnac 环多段PMF 多波长光纤激光器工作的延伸，其在DWDM 系统，传感和仪表测试中具有潜在应用。

通信外文翻译外文文献英文文献及译文

通信外文翻译外文文献英文文献及译文Communication SystemA generalized communication system has the following components:(a) Information Source. This produces a message which may be written or spoken words, or some form of data.(b) Transmitter. The transmitter converts the message into a signal, the form of which is suitable for transmission over the communication channel.(c) Communication Channel. The communication channel is the medium used transmit the signal, from the transmitter to the receiver. The channel may be a radio link or a direct wire connection.(d) Receiver. The receiver can be thought of as the inverse of the transmitter. Itchanges the received signal back into a message and passes the message on to its destination which may be a loudspeaker，teleprinter or computer data bank.An unfortunate characteristic of all communication channels is that noise is added to the signal. This unwanted noise may cause distorionsof sound in a telephone, or errors in a telegraph message or data.Frequency Diversion MultiplexingFrequency Diversion Multiplexing(FDM) is a one of analog technologies. A speech signal is 0~3 kHz, single sideband amplitude (SSB) modulation can be used to transfer speech signal to new frequency bands,four similar signals, for example, moved by SSB modulation to share the band from 5 to 20 kHz. The gaps between channels are known as guard spaces and these allow for errors in frequency, inadequate filtering, etc in the engineered system.Once this new baseband signal, a "group" of 4 chEmnels, has been foimed it ismoved around the Lrunk network as a single unit. A hierarchy can be set up withseveral channels fonning a "group". several groups a "supergroup" and several"supergraup" eicher a "nmsrergroup" or "hypergroup".Groups or supergroups are moved around as single units by the communicationsequipment and it is not necessary for the radios to know how many channels are involved. A radio can handle a supergroup provided sufficient bandwidth is available. The size of the groups is a compromise as treating each channel individually involves far more equipment because separate filters, modulators and oscillators are required for every channel rather than for each group. However the failure of one module will lose all of the channels associated with a group.Time Diversion MultiplexingIt is possible, with pulse modulation systems, to use the between samples to transmit signals from other circuits. The technique is knownas time diversion multiplexing (TDM). To do this, it is necessary to employ synchronized switches at eachend of the communication links to enable samples to be transmittedin turn, from each of several circuits. Thus several subscribers appear to use the link simultaneously. Although each user only has periodic short time slots, the original analog signalsbetween samples can be reconstituted at the receiver.Pulse Code ModulationIn analog modulation, the signal was used to modulate the amplitude or frequency of a carrier, directly. However, in digital modulation a stream of pulse, representing the original，is created. This stream is then used to modulate a carrier or alternatively is transmitted directly over a cable. Pulse Code Modulation (PCM) is one of the two techniques commonly used.All pulse systems depend on the analog waveform being sampled at regular intervals. The signal created by sampling our analog speech input is known as pulse amplitude modulation. It is not very useful in practice but is used as an intermediate stage towards forming a PCM signal. It will be seen later that most of the advantages of digital modulation come from the transmitted pulses having two levels only, this being known as a binary system. In PCM the height of each sample is converted into a binary number. There are three step in the process of PCM: sampling, quantizing and coding.Optical Fiber CommunicationsCommunication may be broadly defined as the transfer of information from one point to another. When the information is to be conveyed over any distance acommunication system is usually required. Within a communication system the information transfer is frequently achieved by superimposing or modulating the information on to an electromagnetic wave which acts as a carrier for the informationsignal. This modulated carrier is then transmitted to the required destination where it is received and the original information signal is obtained by demodulation. Sophisticated techniques have been developed for this process by using electromagnetic carrier wavesoperating at radio frequencies as well as microwave and millimeter wave frequencies. However，拻 communication?may also be achieved by using an electromagneticcarrier which is selected from the optical range of frequencies.In this case the information source provides an electrical signal to a transmitter comprising an electrical stage which drives an optical source to give modulation of the light-wave carrier. The optical source which provides the electrical-optical conversionmay be either a semiconductor laser or light emitting diode (LED). The transmission medium consists of an optical fiber cable and the receiver consists of an optical detector which drives a further electrical stage and hence provides demodulation optical carrier. Photodiodes (P-N, P-I-N or avalanche) and , in some instances,phototransistor and photoconductors are utilized for the detection of the optical signal and the electrical-optical conversion. Thus there is a requirement for electrical interfacing at either end of the optical link and at present the signal processing is usually performed electrically.The optical carrier may be modulated by using either an analog or digital information signal. Analog modulation involves the variation of the light emitted from the optical source in a continuous manner. With digital modulation, however, discrete changes in the light intensity are obtained (i.e. on-off pulses). Although often simpler to implement, analog modulation with an optical fiber communication system is lessefficient, requiring a far higher signal to noise ratio at the receiver than digital modulation. Also, the linearity needed for analog modulation is not always provided by semiconductor optical source, especially at high modulation frequencies. For thesereasons，analog optical fiber communications link are generally limited to shorter distances and lower bandwidths than digital links.Initially, the input digital signal from the information source is suitably encoded for optical transmission. The laser drive circuit directly modulates the intensity of the semiconductor laser with the encoded digital signal. Hence a digital optical signal is launched into the optical fiber cable. The avalanche photodiode detector (APD) is followed by a fronted-end amplifier and equalizer orfilter to provide gain as well as linear signal processing and noise bandwidth reduction. Finally, the signal obtained isdecoded to give the original digital information.Mobile CommunicationCordless Telephone SystemsCordless telephone system are full duplex communication systems that use radio to connect a portable handset to a dedicated base station，which is then connected to adedicated telephone line with a specific telephone number on the public switched telephone network (PSTN) .In first generation cordless telephone systems5(manufactured in the 1980s), the portable unit communications only to the dedicatedbase unit and only over distances of a few tens of meters.Early cordless telephones operate solely as extension telephones to a transceiver connected to a subscriber line on the PSTN and are primarily for in-home use.Second generation cordless telephones have recently been introduced which allowsubscribers to use their handsets at many outdoor locations within urban centers such as London or Hong Kong. Modern cordless telephones are sometimes combined with paging receivers so that a subscriber may first be paged and then respond to the pageusing the cordless telephone. Cordless telephone systems provide the user with limited range and mobility, as it is usually not possible to maintain a call if the user travels outside the range of the base station. Typical second generation base stations provide coverage ranges up to a few hundred meters.Cellular Telephone SystemA cellular telephone system provides a wireless connection to the PSTN for any user location within the radio range of the system.Cellular systems accommodate alarge number of users over a large geographic area, within a limited frequency spectrum. Cellular radio systems provide high quality service that is often comparable to that of the landline telephone systems. High capacity is achieved by limiting the coverage of each base station transmitter to a small geographic area called a cell so that the same radio channels may be reused by another base station located some distance away. A sophisticated switching technique called a handoff enables a call to proceeduninterrupted when the user moves from one cell to another.A basic cellular system consists of mobile station, base stations and a mobile switching center (MSC). The Mobile Switching Center is sometimes called a mobiletelephone switching office (MTSO), since it is responsible for connecting all mobiles to the PSTN in a cellular system. Each mobilecommunicates via radio with one of the base stations and may be handed-off to any number of base stations throughout the duration of a call. The mobile station contains a transceiver, an antenna, and control circuitry，and may be mounted in a vehicle or used as a portable hand-held unit. Thebase stations consists of several transmitters and receivers which simultaneously handlefull duplex communications and generally have towers which support several transmitting and receiving antennas. The base station serves as a bridge between all mobile users in the cell and connects the simultaneous mobile calls via telephone linesor microwave links to the MSC. The MSC coordinates the activities of all the base stations and connects the entire cellular system to the PSTN. A typical MSC handles 100000 cellular subscribers and 5000 simultaneous conversations at a time, andaccommodates all billing and system maintenance functions, as well. In large cities, several MSCs are used by a single carrier.Broadband CommunicationAs can be inferred from the examples of video phone and HDTV, the evolution offuture communications will be via broadband communication centered around video signals. The associated services make up a diverse set of high-speed and broadbandservices ranging from video services such as video phone，video conferencing，videosurveillance, cable television (CATV) distribution, and HDTV distribution to the high-speed data services such as high-resolution image transmission, high-speed datatransmission, and color facsimile. The means of standardizing these various broadbandcommunication services so that they can be provided in an integrated manner is no other than the broadband integrated services digital network (B-ISDN). Simple put, therefore,the future communications network can be said to be a broadband telecommunicationsystem based on the B-ISDN.For realization of the B-ISDN, the role of several broadband communicationtechnologies is crucial. Fortunately, the remarkable advances in the field of electronics and fiber optics have led to the maturation of broadband communication technologies.As the B-ISDN becomes possible on the optical communication foundation, the relevant manufacturing technologies for light-source and passive devices and for optical fiberhave advanced to considerable levels. Advances in high-speed device and integratedcircuit technologies for broadband signal processing are also worthy of close attention. There has also been notable progress in software, signal processing, and video equipment technologies. Hence, from the technological standpoint, the B-ISDN hasfinally reached a realizable state.On the other, standardization activities associated with broadband communication have been progressing. The Synchronous Optical Network (SONET) standardization centered around the T1 committee eventually bore fmit in the form of the Synchronous Digital Hierarchy (SDH) standards of the International Consultative Committee in Telegraphy and Telephony (CCITT), paving the way for synchronous digital transmission based on optical communication. The standardization activities of the 5integrated services digital network (ISDN), which commenced in early 1980s with the objective of integrating narrowband services, expanded in scope with the inclusion of broadband services, leading to the standardization of the B-ISDN in late1980抯 and establishing the concept of asynchronous transfer mode (ATM)communication in process. In addition, standardization of various video signals is becoming finalized through the cooperation among such organizations as CCITT, the International Radio-communications Consultative Committee (CCIR), and theInternational Standards Organization (ISO), and reference protocols for high-speedpacket communication are being standardized through ISO, CCITT, and the Institute of Electrical and Electronics Engineer (IEEE).Various factors such as these have made broadband communication realizable.5Therefore, the 1990s is the decade in which matured broadband communicationtechnologies will be used in conjunction with broadband standards to realize broadband communication networks. In the broadband communication network, the fiber opticnetwork will represent the physical medium for implementing broadband communication, while synchronous transmission will make possible the transmission of broadband service signals over the optical medium. Also, the B-ISDN will be essentialas the broadband telecommunication network established on the basis of optical medium and synchronous transmission and ATM is the communication means that enables the realization of the B-ISDN. The most important of the broadband services to be providedthrough the B-ISDN are high-speed data communication services and videocommunication services.Image AcquisitionA TV camera is usually used to take instantaneous images and transform them into electrical signals, which will be further translated into binary numbers for the computer to handle. The TV camera scans oneline at a time. Each line is further divided into hundreds of pixels. The whole frame is divided into hundreds (for example, 625) of lines.The brightness of a pixel can be represented by a binary number with certain bits, for example, 8 bits. The value of the binary number varies from 0 to 255, a range great enough to accommodate all possible contrast levels of images taken from real scene.These binary numbers are sorted in an RAM (it must have a great capacity) ready for processing by the computer.Image ProcessingImage processing is for improving the quality of the images obtained. First, it is necessary to improve the signal-to-noise ratio. Here noise refers to any interference flaw or aberation that obscure the objects on the image. Second, it is possible to improve contrast, enhance sharpness of edges between images through various computational means.Image AnalysisIt is for outlining all possible objects that are included in the scene. A computer program checks through the binary visual informationin store for it and identifies specific feature and characteristics of those objects. Edges or boundaries are identifiablebecause of the different brightness levels on either side of them. Usingcertain algorithms, the computer program can outline all possible boundaries of the objects in the scene. Image analysis also looks for textures and shadings between lines.Image ComprehensionImage Comprehension means understanding what is in a scene. Matching the prestored binary visual information with certain templates which represent specific objects in a binary form is technique borrowed from artificial intelligence, commonly referred to as "templeite matching"emplate matching? One by one,the templates are checked against the binary information representing the scene. Once a match occurs, an object is identified. The template matching process continues until all possible objects in the scene have been identified, otherwise it fails.通信系统一般的通信系统由下列部分组成:信源。

通信毕设中英文文献翻译

英文文献The Application of one point Multiple Access Spread SpectrumCommunication SystemLiu Jiangang, Nan yang City, Henan Province Electric Power Industry Bureau【ABSTRACT】Spread Spectrum Digital Microwave communication as a communication, because their excellent performance have been widely used. The article in Nan yang City Power Industry Bureau one point Multiple Access Spread Spectrum Communication System as an example. briefed the spread spectrum communications, the basic concept and characteristics of the power system communication applications.KEYWORDS：one point multiple access; Spread-spectrum communication; AttenuationNan yang City in the outskirts of Central cloth 35 to 11 kv substation farm terminals, their operation management rights belong to the Council East, Rural Power Company west (the eastern suburb of agricultural management companies -- four, the western suburbs of Rural Power Company Management 7), Scheduling of the various stations of the means of communication to the original M-150 radio and telephone posts. 2002 With the transformation of rural network, the remote station equipment into operation and communication channels to put a higher demand .As PUC Dispatch Communication Building to the east and west of farmers -- the difference between a company linked to fiber, Therefore, if 11 substations and the establishment of a transfer Link Building links Point may be the data and voice were sent to two rural power companies dispatch room, Rural Network scheduling for the implementation of automation to create the necessary conditions.Given the status and power grid substation level, nature, taking into account the carrier and optical-fiber communications to conduct multiple forwarding, increasing the instability factor, considering the cost and conditions of the urban construction, Finallydecided to adopt wireless spread-spectrum technology to establish that 11 farm terminal substation communication system. This paper describes the spread spectrum technology and the current system of the building.1.The basic concept of spread-spectrum communication.Spread Spectrum Communication's basic characteristics, is used to transmit information to the signal bandwidth (W) is far greater than the practical information required minimum (effective) bandwidth (△ F) , as the ratio of processing gain GP .G P = W/△FAs we all know, the ordinary AM, FM, or pulse code modulation communications, GP values in the area more than 10 times, collectively, the "narrow-band communication", and spread-spectrum communications GP values as high as hundreds or even thousands of times, can be called "broadband communications."Due to the spread-spectrum signal, it is very low power transmitters, transmission space mostly drowned in the noise, it is difficult to intercepted by the other receiver, only spreading codes with the same (or random PN code) receiver, Gain can be dealt with, and dispreading resume the original signal.2.The technology superiority of spread-spectrum communication.Strong anti-interference, bit error rate is low. As noted above, the spread spectrum communication system due to the expansion of the transmitter signal spectrum, the receiver dispreading reduction signal produced spreading gain, thereby greatly enhancing its interference tolerance. Under the spreading gain, or even negative in the signal-to-noise ratio conditions, can also signal from the noise drowned out Extraction, in the current business communications systems, spread spectrum communication is only able to work in a negative signal-to-noise ratio under the conditions of communication.Anti-multi-path interference capability, increase the reliability of the system. Spread-spectrum systems as used in the PN has a good correlation, correlation is very weak. different paths to the transmission signal can easily be separated and may in time and re-alignment phase, formation of several superimposed signal power, thereby improving the system's performance to receive increased reliability of the system.Easy to use the same frequency, improving the wireless spectrum utilization.Wireless spectrum is very valuable, although long-wave microwave have to be exploited, and still can not meet the needs of the community. To this end, countries around the world are designed spectrum management, users can only use the frequency applications, rely on the channel to prevent the division between the channel interference.Due to the use of spread-spectrum communication related receive this high-tech, low signal output power ( "a W, as a general-100 mW), and will work in the channel noise and thermal noise in the background, easy to duplicate in the same area using the same frequency, can now all share the same narrow-band frequency communications resources.Spread spectrum communication is digital communications, particularly for digital voice and data transmission while, spread spectrum communication with their own encryption, only in the same PN code communication between users, is good for hiding and confidential in nature, facilitating communications business . Easy to use spread-spectrum CDMA communications, voice compression and many other new technologies, more applicable to computer networks and digitization of voice, image information transmission.Communication is the most digital circuits, equipment, highly integrated, easy installation, easy maintenance, but also very compact and reliable. The average failure rate no time was very long.We have decided to adopt the spread-spectrum communication technology construction of 11 farm terminal substation communications system, Due to the spread-spectrum communication by the line-of-sight transmission distance restrictions, has become unstoppable system design premise.If the PUC scheduling Building and 11 substations have stopped, and the problem becomes more complicated, use spread spectrum system on the feasibility greatly reduced. Therefore, we look at the city Aerial topographical map, initially identified has not stopped to consider systems design, and requests the companies used this equipment Spread Spectrum 11 points transmission routing of the measured and the results have been satisfactory.Then spread spectrum wireless equipment market supply of cash, initially, weselected a series of Spread Spectrum Comlink third generation products. Because most of the point-to-point mode, Merit functions of the spread-spectrum equipment in a point-to-multipoint application environments encountered many problems: First is the issue of frequency resources. Even a minimum of 64 kbit / s data rate radio, space also occupied bandwidth 5 MHz, Because 32 of the PN code isolation is only about 15 dBm, the project had to use frequency division multiple access 35 db to get around the theoretical isolation. 11 stations will use 11 frequencies, frequency greater waste of resources. Comlink and Spread Spectrum products in the same frequency to achieve a point-to-multipoint communications.Second antenna erection problems, point-to-point equipment for the main radio station, the main station need to set up a number of terminal antennas, the vast majority of domestic engineering companies used by the U.S. Conifer 24 dBi parabolic semi-cast magnesium grid directional antenna. vertical polarization - 1 m wide, it is difficult to top the layout and avoid flap and the mutual interference, Although the project can be set up to take stratified, or through cooperation and on the road to one or more Omni directional antenna launch, However, as construction of a road and the signal attenuation, transmission result is not satisfactory.In addition, the RF cable lying, The application of network management software such factors we have also decided to adopt the final 1:00 Comlink Multiple Access Spread Spectrum products. Its system configuration, as shown in Figure 2:3.Routing AnalysisCombining visual distance access and use the radio and antenna gain, cable attenuation and environmental factors, and testing the design is reasonable, determinethe attenuation affluent channel capacity. Spread spectrum microwave link attenuation depends on the reliability margin.Attenuation margin calculation formula : F G= G SG + G ANT - L GL - L PLF G——Attenuation margin ；G SG——System Gain (dB）；G ANT——Antenna Gain (dBi）；L GL——Connectors and cables attenuation (dB)；L pL—— Channel attenuation (dB）。

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使用LabVIEW中的TCP/IP和UDP协议前言互联网络协议(IP)，用户数据报协议(UDP)和传输控制协议(TCP)是网络通信的基本的工具。

TCP与IP的名称来自于一组最著名的因特网协议中的两个--传输控制协议和互联网络协议。

你能使用TCP/IP来进行单一网络或者互连网络间的通信。

单独的网络会被大的地理距离分隔。

TCP/IP把数据从一个子网网络或者因特网连接的计算机发送到另一个上。

因为TCP/IP 在大多数计算机上是可用的，它能在多样化的系统中间传送信息。

LabVIEW和TCP/IP你能在所有平台上的LabVIEW中使用TCP/IP。

LabVIEW包含了TCP和UDP程序还有能让你建立客户端或者服务器程序的功能。

IPIP执行低层次的计算机间的数据传送。

在组成部分里的IP数据包称为数据报。

一个数据报包含表明来源和目的地地址的数据和报头字。

IP为通过网络或者因特网把数据发送到指定的目的地的数据报确定正确的路径。

IP协议并不能保证发送。

事实上，如果数据报在传输中被复制，IP可能多次传送一个单独的数据报。

所以，程序很少用IP而是用TCP或者UDP代替。

UDPUDP在计算机进程中提供简单而低层次的通信。

进程通过把数据报发送到一个目的地计算机或者端口进行通信。

一个端口是你发送数据的位置。

IP处理计算机对计算机的发送。

在数据报到达目的地计算机后，UDP把数据报移动到其目的端口。

如果目的端口不是开放的，UDP 将删除数据报。

UDP将发生IP的同样的发送问题。

应用程序的UDP的可靠性不强。

例如，一项应用程序能经常把大量信息的数据传送到目的地而丢失少量的数据是肯定的。

在LabVIEW中使用UDP协议因为UDP不是一个TCP似的一个以连接为基础的协议，在你发送或者收到数据之前，你不需要和目的地建立一种连接。

相反，当你每发送一个数据报时，由你指定数据目的地。

操作系统不会报告传输差错使用UDP打开功能在一个端口上打开一个UDP插口。

同时打开的UDP端口的数量仍依赖于操作系统。

UDP的打开的功能返回到网络连接时唯一识别UDP套接字。

使用这种连接在子VI程序中就是靠这个套接字。

用UDP编写功能发送数据到目的地，然后使用UDP阅读功能阅读那个数据。

每写一个操作要求一个目的地地址和端口。

每阅读一个操作包含来源地址和端口。

UDP保存你所发送的每一个命令所指定的数据报字节。

在理论上，你能发送任何大小的数据报。

然而，你最好不使用UDP来发送大的数据报，因为它不像TCP一样可靠。

当你在一个端口上结束所有通信时，使用UDP结束功能去释放系统资源。

UDP多路广播你能使用UDP的功能来与一个单独的客户端通信或者通过广播对于所有局域网上的计算机通信。

如果你想要传送成倍增加具体的计算机信息，你必须通过客户端列表构建UDP功能反复执行。

因为LabVIEW能把数据的作为一个单独的拷贝发送到每个客户端并且保存对收到数据感兴趣的客户端列表，所以运用这种技术建立完全相同的网络交换。

使用多路广播可以在网络上的进行单个的发送端和多倍的客户端之间的通信而不需要保存客户列表或者要求发送端把数据多重拷贝后发送给每个客户端。

为了通过多路广播收到数据广播，所有客户端必须加入一个多路广播组。

而发送端不需要加入该组。

发送端只需规定一个多路广播的IP地址来定义这个多路广播组。

多路广播的IP地址范围在224.0.0.0到239.255.255.255中。

当一个客户端想要加入一个多路广播组时，它只需预定这个组的多路广播的IP地址。

在客户端预定到一个多路广播组之后，客户端收到从多路广播的IP 地址发送的数据。

对于LabVIEW中的多路广播，使用UDP多路广播的打开程序有能力读、写或者读和写UDP 数据。

规定TTL为写数据，多路广播地址为读数据，多路广播端口号为读写数据。

默认TTL 是1，这意味着LabVIEW仅仅把数据报发送到本地的网络上。

当一个发送方收到一个多路广播数据报时，它消耗数据报的生存时间。

如果TTL大于1，发送方把数据报转发到其它数据报。

下面的表格说明了当你规定一个TTL的值时，一个多路广播数据报的运行。

0 主机上还存留数据报1 数据报发送到每个在同一本地网络上已预定那个IP地址的客户端。

中枢/转发器和桥路/开关转发数据报。

发送方不转发数据报如果TTL为1。

如果你规定一个值大于1，数据报通过TTL-1层被发送，并且发送方转发它。

参阅在LabVIEW\例子\comm\UDP.llb中的UDP多路广播接受方程序和UDP多路广播发送方程序VI中使用UDP多路广播的例程。

TCPTCP保证在网络中的可靠的通信，按顺序发送而没有差错，损失或者重发。

TCP直到收到一个确认才转发。

系统要求在使用TCP/IP之前，确认你有必需的要求，这变化依赖于你使用的平台。

(Windows和UNIX系统)TCP/IP。

你不需要使用第三种产品连接使用TCP/IP。

如果你的网络适当地被构成，LabVIEW没有要求附加的设置。

(Mac OS系统) LabVIEW网络要求打开传送，包括Mac OS 7.5和更新的版本。

在LabVIEW中使用TCPTCP是一个以连接为基础的协议，这意味着站点必须在传送数据之前建立一种连接。

TCP许可多重、同时的连接。

你可以通过等待一种输入的连接或者通过积极地寻求一种与指定的地址连接建立连接。

在建立TCP连接时，你必须指定一个地址和该地址的端口。

端口范围在0到65,535点之间。

UNIX系统为特殊的应用程序保留端口数少于1,024。

在一个给定的地址中不同的端口能识别不同的服务。

使用TCP的打开连接功能来与一个指定地址进行积极的连接。

如果连接成功，功能返回网络连接的返回数唯一识别那个连接。

使用这种连接refnum来访问子VI程序。

你能使用如下技术来等输入连接：用TCP听程序创建立一个听者并且在一个指定的端口等待一种可接受的TCP连接。

如果连接成功，VI程序返回连接数，地址和远程TCP客户端口。

TCP创建听者功创建一个听者然后用TCP的听者功能上等待的一个听者接受新的连接。

在听者功能上的TCP等待返回你所发送的功能和返回数的同样的听者ID。

当你结束等候新的连接时，用TCP关闭连接功能区关闭一个听者。

你不能对一个听者进行读写。

用第二种技术的优势是你能使用TCP关闭连接功能来取消听操作，这在你想要为了一种连接听而没有超时，但是你想要取消当另一个条件变真时的听时是很有用的。

你能在任何时间关闭听程序。

当你建立一种连接时，用TCP读功能和TCP写功能能在远程应用中队数据进行读写。

用TCP关闭连接功能区关闭远程连接。

如果没被读的仍保留着而关闭连接，你可能失去数据。

当关闭连接时，在你的计算机上使用较高层次协议。

在连接被关闭后，你不能再读写它。

TCP和UDP之间的区别在你想要可靠的数据传输时，TCP是最好的协议。

UDP是高性能的无需连接的协议，但是它不保证可靠性。

建立TCP客户端注意：请参考最近的版本LabVIEW帮助功能对这些指令和功能的细节描述。

完成如下步骤使用TCP功能建立一个TCP顾客。

1.用TCP的打开连接功能来打开一个服务器的连接。

你必须规定服务器的因特网地址和服务器的端口。

地址在网络上识别计算机。

远程端口在服务器使用听的计算机上识别一个通信通道。

当你建立一个TCP服务器时，你要规定你想要服务器为通信使用的端口。

2.用TCP的写功能把信息发送到服务器上。

3.用TCP的读功能来读发自服务器的信息。

你必须规定你想读的字节数。

4.用TCP的关闭功能来关闭与服务器的连接。

请参阅labview\examples\comm\TCP.llb中对单一数据客户端的TCP例程。

超时和差错当你设计一种网络应用时，应细心考虑失败是如何发生的。

例如，如果服务器被毁，确定如何使每个客户VI程序掌控它。

一种解决方式是确保每个客户VI程序有超时功能。

如果发生没能在一定量的时间之后生产结果，客户端继续执行。

在继续时，客户端能试图重建连接或者报告出错。

如果必要的话，客户端VI程序能关闭应用程序。

建立TCP服务器注意：请参考最近的版本LabVIEW帮助功能对这些指令和功能的细节描述。

完全如下步骤用TCP功能来建立一个TCP服务器。

1.使用TCP听程序等待连接。

你必须规定端口。

这个端口必须是客户端试图访问的同一个端口。

2.如果连接被建立，用TCP读功能从接受到信息的端口读信息。

3.用TCP写功能返回结果。

数据必须是一种客户端能接受的形式。

4.用TCP关连接功能来关闭连接。

请参阅labview\examples\comm\TCP.llb中对单一数据客户端的TCP例程。

TCP和UDP例子请参阅labview\examples\comm\TCP.llb和labview\examples\comm\UDP.llb中用TCP和UDP的VI程序和功能。

Application Note 160 Using LabVIEW™ with TCP/IP and UDP IntroductionInternet Protocol (IP), User Datagram Protocol (UDP), and Transmission Control Protocol (TCP) are basic tools for network communication. The name TCP/IP comes from two of the best-known protocols of the Internet protocol suite, the Transmission Control Protocol and the Internet Protocol.You can use TCP/IP to communicate over single networks or interconnected networks. The individual networks can be separated by large geographical distances. TCP/IP routes data from one network or Internet-connected computer to another. Because TCP/IP is available on most computers, it can transfer information among diverse systems.LabVIEW and TCP/IPYou can use the TCP/IP protocols with LabVIEW on all platforms. LabVIEW includes TCP and UDP VIs and functions you can use to create client or server VIs.IPIP performs the low-level service of moving data between computers. IP packages data into components called datagrams.A datagram contains the data and a header that indicates the source and destination addresses. IP determines the correct path for the datagram to take across the network or Internet and sends the data to the specified destination.IP cannot guarantee delivery. In fact, IP might deliver a single datagram more than once if the datagram is duplicated in transmission. Programs rarely use IP but use TCP or UDP instead.UDPUDP provides simple, low-level communication among processes on computers. Processes communicate by sending datagrams to a destination computer or port. A port is the location where you send data. IP handles thecomputer-to-computer delivery. After the datagram reaches the destination computer, UDP moves the datagram to its destination port. If the destination port is not open, UDP discards the datagram. UDP shares the same delivery problems of IP.Use UDP in applications in which reliability is not critical. For example, an application might transmit informative data to a destination frequently enough that a few lost segments of data are not problematic.LabVIEW™, National Instruments™, and ™ are trademarks of National Instruments Corporation. Product and company names mentioned herein are trademarks or trade names of their respective companies. For patents covering National Instruments products, refer to the appropriate location: Help»Patents in your software, thepatents.txt file on your CD, or /patents.342028C-01 © 2000–2004 National Instruments Corporation. All rights reserved. March 2004Using UDP in LabVIEWBecause UDP is not a connection-based protocol such as TCP, you do not need to establish a connection with a destination before you send or receive data. Instead, you specify the destination for the data when you send each datagram. Operating systems do not report transmission errors.Use the UDP Open function to open a UDP socket on a port. The number of simultaneously open UDP ports dependson the operating system. The UDP Open function returns a network connection refnum that uniquely identifies theUDP socket. Use this connection refnum to refer to this socket in subsequent VI calls.Use the UDP Write function to send data to a destination, and use the UDP Read function to read that data. Each write operation requires a destination address and port. Each read operation contains the source address and port. UDP preserves the datagram bytes that you specified for each command you send.In theory, you can send datagrams of any size. However, you typically would not use UDP to send large datagrams because it is not as reliable as TCP.When you finish all communications on a port, use the UDP Close function to free system resources.UDP MulticastYou can use the UDP functions to communicate to a single client (single-cast) or to all computers on the subnet througha broadcast. If you want to communicate to multiple specific computers, you must configure the UDP functions to iterate through a list of clients. Using this technique creates duplicate network traffic because LabVIEW sends a separate copy of the data to each client and maintains a list of clients interested in receiving the data.Use multicasting to communicate between a single sender and multiple clients on a network without requiring the sender to maintain a list of clients or send multiple copies of the data to each client. To receive data broadcast by a multicast sender, all clients must join a multicast group. The sender does not have to join a group to send data. The sender specifies a multicast IP address, which defines a multicast group. Multicast IP addresses are in the 224.0.0.0to 239.255.255.255 range. When a client wants to join a multicast group, it subscribes to the multicast IP addressof the group. After subscribing to a multicast group, the client receives data sent to the multicast IP address.To multicast in LabVIEW, use the UDP Multicast Open VI to open connections capable of reading, writing, or reading and writing UDP data. Specify the time-to-live (TTL) for writing data, the multicast address for reading data, and the multicast port number for reading and writing data. The default TTL is 1, which means LabVIEW sends the datagram only to the local subnet. When a router receives a multicast datagram, it decrements the datagram TTL. If the TTL is greater than 1, the router forwards the datagram to other routers. The following table lists what action occurs to a multicast datagram when you specify a value for the time-to-live parameter.Datagram remains on the host computer.1 Datagram sent to every client on the same local subnet that subscribes to that IP address. Hubs/repeatersand bridges/switches forward the datagram. Routers do not forward the datagram if the TTL is 1.Application Note 160 2 If you specify a value greater than 1, the datagram is sent and routers forward it through TTL-1 layers.Refer to the UDP Multicast Receiver VI and the UDP Multicast Sender VI in the labview\examples\comm\UDP.llb for examples of using UDP multicasting.TCPTCP ensures reliable transmission across networks, delivering data in sequence without errors, loss, or duplication.TCP retransmits the datagram until it receives an acknowledgment.System RequirementsBefore using TCP/IP, confirm that you have the necessary requirements, which vary depending on the platform you use.(Windows and UNIX) TCP/IP is built in. You do not need to use a third-party product to communicate using TCP/IP.If your network is configured properly, LabVIEW requires no additional setup.(Mac OS) LabVIEW networking requires Open Transport, included in Mac OS 7.5 and later.Using TCP in LabVIEWTCP is a connection-based protocol, which means that sites must establish a connection before transferring data. TCP permits multiple, simultaneous connections.You initiate a connection by waiting for an incoming connection or by actively seeking a connection with a specified address. In establishing TCP connections, you have to specify the address and a port at that address. A number between 0 and 65,535 represents a port. UNIX reserves port numbers less than 1,024 for privileged applications. Different ports at a given address identify different services at that address.Use the TCP Open Connection function to actively establish a connection with a specific address and port. If the connection is successful, the function returns a network connection refnum that uniquely identifies that connection.Use this connection refnum to refer to the connection in subsequent VI calls.You can use the following techniques to wait for an incoming connection:Use the TCP Listen VI to create a listener and wait for an accepted TCP connection at a specified port. If theconnection is successful, the VI returns a connection refnum, the address, and the port of the remote TCP client.Use the TCP Create Listener function to create a listener and use the TCP Wait on Listener function to listen for and accept new connections. The TCP Wait on Listener function returns the same listener ID you wired to the function and the connection refnum for a connection. When you finish waiting for new connections, use the TCP Close Connection function to close a listener. You cannot read from or write to a listener.The advantage of using the second technique is that you can use the TCP Close Connection function to cancel a listen operation, which is useful when you want to listen for a connection without using a timeout, but you want to cancel the listen when another condition becomes true. You can close the listen VI at any time.When you establish a connection, use the TCP Read function and the TCP Write function to read and write data to the remote application.Use the TCP Close Connection function to close the connection to the remote application. If unread data remains and the connection closes, you might lose data. Use a higher level protocol for your computer to determine when to close the connection. After a connection is closed, you cannot read from it or write to it again.© National Instruments Corporation 3 Application Note 160Deciding between TCP and UDPTCP is the best protocol to use if you want reliable data transmission. UDP is a connectionless protocol with higher performance, but it does not ensure reliable data transmission.Creating a TCP ClientNote Refer to the LabVIEW Help for the most recent version of these instructions and details for each of thefunctions.Complete the following steps to create a TCP client using the TCP functions.1. Use the TCP Open Connection function to open a connection to a server. Y ou must specify the Internet address ofthe server and the port for the server.The address identifies a computer on the network. The remote port identifies a communication channel on the computer that the server uses to listen for communication requests. When you create a TCP server, you specify the port that you want the server to use for communication.2. Use the TCP Write function to send a message to a server.3. Use the TCP Read function to read a message from the server. Y ou must specify the number of bytes you want toread.4. Use the TCP Close Connection function to close the connection to the server.Refer to the Simple Data Client VI in the labview\examples\comm\TCP.llb for an example of a TCP client. Timeouts and ErrorsWhen you design a network application, consider carefully what should happen if something fails. For example, if the server crashes, determine how each client VI handles it.One solution is to make sure that each client VI has a timeout. If something fails to produce results after a certain amount of time, the client continues execution. In continuing, the client can try to reestablish the connection or report the error. If necessary, the client VI can shut down the application.Creating a TCP ServerNote Refer to the LabVIEW Help for the most recent version of these instructions and details for each of thefunctions.Complete the following steps to create a TCP server using the TCP functions.1. Use the TCP Listen VI to wait for a connection. You must specify the port. This port must be the same port that theclient attempts to access.2. If a connection is established, use the TCP Read function to read from that port to retrieve a message.3.Use the TCP Write function to return results. The data must be in a form that the client can accept. 4. Use theTCP Close Connection function to close the connection.Refer to the Simple Data Server VI in the labview\examples\comm\TCP.llb for an example of a TCP server. TCP and UDP ExamplesRefer to the labview\examples\comm\TCP.llb and the labview\examples\comm\UDP.llb for examples of using the TCP and UDP VIs and functions.。

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